Patent Publication Number: US-11659916-B2

Title: Mounting base for a wirelessly locatable tag

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application is a continuation patent application of PCT Patent Application No. PCT/US2020/028424, filed Apr. 16, 2020 and titled “Wirelessly Locatable Tag,” which claims priority to U.S. Provisional Patent Application No. 62/835,469, filed Apr. 17, 2019 and titled “Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 62/855,768, filed May 31, 2019 and titled “Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 62/894,640, filed Aug. 30, 2019 and titled “Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 63/101,179, filed Sep. 26, 2019 and titled “Enclosure for a Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 62/922,248, filed Sep. 26, 2019 and titled “Holding Accessory for a Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 63/101,180, filed Sep. 26, 2019 and titled “Audio Output System for a Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 63/101,212, filed Sep. 26, 2019 and titled “Antenna Assembly for a Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 62/922,250, filed Sep. 26, 2019 and titled “Battery Connection System for a Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 63/101,182, filed Sep. 26, 2019 and titled “Mounting Base for a Wirelessly Locatable Tag,” U.S. Provisional Patent Application No. 62/922,249, filed Sep. 26, 2019 and titled “Wirelessly Coupled Accessory System for an Electronic Device,” U.S. Provisional Patent Application No. 63/101,242, filed Sep. 26, 2019 and titled “Fastener with a Constrained Retention Ring,” and U.S. Provisional Patent Application No. 63/101,229, filed Sep. 26, 2019 and titled “Biomechanical Sensing System using Wirelessly Locatable Tags,” the disclosures of which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD 
     The described embodiments relate generally to a mounting base for a wirelessly locatable tag. 
     BACKGROUND 
     Electronic devices like mobile phones and portable computers are used extensively around the world. Traditionally, a geographic location of an electronic device may be determined using a global positioning system (GPS) or other locating system or technique. However, it may be difficult to locate personal property that is not an electronic device or to locate electronic devices that lack a GPS. The systems and techniques described herein are generally directed to a wirelessly locatable tag that may be used to determine the location of electronic devices or other personal property or objects. 
     SUMMARY 
     A mounting base may be used with a wirelessly locatable tag, the wirelessly locatable tag defining a battery cavity configured to receive a button cell battery. The mounting base may include a base portion defining a latching member configured to engage a wirelessly locatable tag to releasably retain the wirelessly locatable tag to the mounting base, a contact block attached to the base portion and configured to be positioned at least partially within a battery cavity of the wirelessly locatable tag, the contact block defining a top side and a peripheral side. The mounting base may further include a first conductive member positioned along the peripheral side of the contact block and configured to contact a first battery contact in the battery cavity of the wirelessly locatable tag, a second conductive member outwardly biased from the top side of the contact block, the second conductive member configured to contact a second battery contact in the battery cavity of the wirelessly locatable tag, and a power cable coupled to the base portion and configured to supply electrical power to the wirelessly locatable tag via the first and second conductive members. 
     The second conductive member may be configured to be deflected by a surface defining the battery cavity when the wirelessly locatable tag is coupled to the mounting base. The second conductive member may be configured to impart a biasing force on a surface of the battery cavity when the wirelessly locatable tag is coupled to the mounting base. The second conductive member may be configured to deflect the first battery contact when the wirelessly locatable tag is coupled to the mounting base. 
     The mounting base may further include power conversion circuitry positioned within a cavity defined in the base portion and configured to change a characteristic of an input current provided by the power cable. The base portion may define a passage configured to fluidly couple an internal volume of the wirelessly locatable tag with an exterior environment when the wirelessly locatable tag is coupled to the mounting base. 
     The mounting base may further include a circuit board, the power cable may be conductively coupled to the circuit board, and the first conductive member and the second conductive member may be conductively coupled to the circuit board. 
     A mounting base for a device may include a latching member configured to engage a retention feature of the device to retain the device to the mounting base, a contact block configured to be positioned at least partially within a battery cavity of the device, the contact block defining a top side and a peripheral side, and a deflectable conductive member extending above the top side of the contact block. The deflectable conductive member may be configured to contact a battery contact that extends into the battery cavity of the device, thereby conductively coupling the deflectable conductive member and the battery contact, and impart a biasing force on the wirelessly locatable tag when the device is coupled to the mounting base, the biasing force configured to bias the latching member against the retention feature of the wirelessly locatable tag. The deflectable conductive member may be at least partially embedded in the contact block. 
     The deflectable conductive member may be a first deflectable conductive member, the biasing force may be a first biasing force, and the mounting base may further include a second deflectable conductive member configured to impart a second biasing force on the device when the device is coupled to the mounting base and a third deflectable conductive member configured to impart a third biasing force on the device when the device is coupled to the mounting base. The second and third biasing forces may be configured to bias the latching member against the retention feature of the device. 
     The mounting base may further include a fourth conductive member coupled to the peripheral side. The fourth conductive member may be conductively coupled to a positive terminal of a DC power supply, and the first, second, and third deflectable conductive members may be conductively coupled to a negative terminal of the DC power supply. 
     The mounting base may further include a power cable configured to supply electrical power to the device via the first, second, and third deflectable conductive members and the fourth conductive member. The power cable may be configured to couple to a DC power supply. The power cable may be configured to couple to an AC power supply, and the mounting base may further include an AC-to-DC converter configured to convert AC power to DC power. 
     A wirelessly locatable system may include a wirelessly locatable tag configured to transmit a wireless signal to an electronic device to facilitate localization of the wirelessly locatable tag by the electronic device, the wirelessly locatable tag defining a battery cavity configured to receive a button cell battery, a positive battery contact extending into the battery cavity, a negative battery contact extending into the battery cavity, and a retention feature configured to engage a first latching member of a battery door. The wirelessly locatable system may further include a mounting base comprising a base portion defining a second latching member configured to engage the retention feature to retain the wirelessly locatable tag to the mounting base, and a contact block attached to the base portion and configured to be positioned at least partially within the battery cavity of the wirelessly locatable tag, the contact block defining a circular top wall and a peripheral side wall extending from a periphery of the circular top wall. The mounting base may further include a first conductive member configured to contact the positive battery contact and a second conductive member configured to contact the negative battery contact. 
     The peripheral side wall may define a curved outer surface having a diameter equal to a curved outer surface of the button cell battery. The second conductive member may be flexible and may be configured to be deflected by a surface of the battery cavity when the wirelessly locatable tag is coupled to the mounting base. The second conductive member may be configured to impart a biasing force on the surface of the battery cavity when the wirelessly locatable tag is coupled to the mounting base, thereby biasing the second latching member against the retention feature. The mounting base may further include a biasing member configured to bias the second latching member against the retention feature. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will be readily understood by the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like structural elements, and in which: 
         FIG.  1    depicts an example system for locating a wirelessly locatable tag; 
         FIGS.  2 A- 2 C  depict an example public-private key encryption scheme for locating a wirelessly locatable tag; 
         FIGS.  2 D- 2 F  depict example localization processes for a wirelessly locatable tag; 
         FIG.  3 A  depicts a top view of an example wirelessly locatable tag; 
         FIG.  3 B  depicts a side view of the example wirelessly locatable tag of  FIG.  3 A ; 
         FIG.  3 C  depicts an exploded view of the example wirelessly locatable tag of  FIG.  3 A ; 
         FIG.  4    depicts a cross-sectional view of an example wirelessly locatable tag; 
         FIG.  5 A  depicts an example wirelessly locatable tag; 
         FIG.  5 B  depicts a cross-sectional view of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  6    depicts an exploded view of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  7    depicts a partial cross-sectional view of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  8 A  depicts an example antenna assembly of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  8 B  depicts another example antenna assembly for a wirelessly locatable tag; 
         FIG.  8 C  depicts a partial cross-sectional view of the antenna assembly of  FIG.  8 A ; 
         FIG.  8 D  depicts an example housing member with antennas for a wirelessly locatable tag; 
         FIG.  8 E  depicts an example wirelessly locatable tag; 
         FIG.  8 F  depicts an example housing member of the wirelessly locatable tag of  FIG.  8 E ; 
         FIG.  9    depicts a partial exploded view of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  10 A  depicts a circuit board of the wirelessly locatable tag of  FIG.  5 A ; 
         FIGS.  10 B- 10 C  depict a battery connector of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  10 D  depicts another example battery connector of the wirelessly locatable tag of  FIG.  5 A ; 
         FIGS.  11 A- 11 D  depict other example battery connector arrangements for a wirelessly locatable tag; 
         FIG.  12 A  depicts a partial exploded view of the wirelessly locatable tag of  FIG.  5 A ; 
         FIGS.  12 B- 12 C  depict operations of a latching member of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  13 A  depicts an example compliant member of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  13 B  depicts a partial cross-sectional view of a portion of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  13 C  depicts another example compliant member for a wirelessly locatable tag; 
         FIGS.  14 A- 16 D  depict an example mechanism for securing a battery door of a wirelessly locatable tag; 
         FIGS.  17 A- 19 E  depict another example mechanism for securing a battery door of a wirelessly locatable tag; 
         FIGS.  20 A- 22 D  depict another example mechanism for securing a battery door of a wirelessly locatable tag; 
         FIGS.  23 A- 23 E  depict another example mechanism for securing a battery door of a wirelessly locatable tag; 
         FIGS.  24 A- 24 C  depict another example mechanism for securing a battery door of a wirelessly locatable tag; 
         FIGS.  25 A- 25 C  depict another example mechanism for securing a battery door of a wirelessly locatable tag; 
         FIGS.  26 A- 26 B  depict aspects of an example audio system of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  27 A  depicts an exploded view of a magnet assembly of the wirelessly locatable tag of  FIG.  5 A ; 
         FIG.  27 B  depicts a partial cross-sectional view of the wirelessly locatable tag of  FIG.  5 A ; 
         FIGS.  28 A- 28 D  depict example coil configurations for an audio system for a wirelessly locatable tag; 
         FIGS.  29 A- 30    depict other example audio systems for a wirelessly locatable tag; 
         FIGS.  31 A- 31 C  depict an example top housing member for a wirelessly locatable tag; 
         FIGS.  32 A- 32 C  depict another example top housing member for a wirelessly locatable tag; 
         FIGS.  33 A- 33 C  depict another example top housing member for a wirelessly locatable tag; 
         FIGS.  34 A- 34 C  depict another example top housing member for a wirelessly locatable tag; 
         FIGS.  35 A- 35 E  depict an example configuration for a wirelessly locatable tag; 
         FIGS.  36 A- 36 B  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  37 A- 37 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  38 A- 38 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  39 A- 39 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  40 A- 40 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  41 A- 41 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  42 A- 42 B  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  43 A- 43 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  44 A- 44 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  45 A- 45 B  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  46 A- 46 B  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  47 A- 47 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  48 A- 48 B  depict a partial cross-sectional view of the tag of  FIGS.  47 A- 47 C ; 
         FIGS.  49 A- 49 B  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  50 A- 50 B  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  51 A- 51 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  52 A- 52 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  53 A- 53 C  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  54 A- 54 B  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  55 A- 55 B  depict another example configuration for a wirelessly locatable tag; 
         FIGS.  56 A- 56 B  depict another example configuration for a wirelessly locatable tag; 
         FIG.  57    depicts another example configuration for a wirelessly locatable tag; 
         FIGS.  58 A- 58 C  depict another example configuration for a wirelessly locatable tag; 
         FIG.  59    depicts a rechargeable wirelessly locatable tag; 
         FIG.  60    depicts another rechargeable wirelessly locatable tag; 
         FIGS.  61 A- 65 B  depict an example mounting base system for wirelessly locatable tags; 
         FIG.  66    depicts another example mounting base system for wirelessly locatable tags; 
         FIG.  67    depicts another example mounting base system for wirelessly locatable tags; 
         FIG.  68    depicts an example contact block for a mounting base system; 
         FIGS.  69 A- 69 C  depict an example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  69 D- 69 G  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  70 A- 70 D  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  71 A- 71 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  72 A- 72 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  73 A- 73 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  74 A- 74 F  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  75 A- 75 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  76 A- 76 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  77 A- 77 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  78 A- 78 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  79 A- 79 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  80 A- 80 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  81 A- 81 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  82 A- 82 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  83 A- 83 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIG.  84 A  depicts another example tag retainer for holding a wirelessly locatable tag; 
         FIG.  84 B  depicts another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  85 A- 85 B  depict an example spring member for attaching to a wirelessly locatable tag; 
         FIGS.  86 A- 86 D  depict another example spring member for attaching to a wirelessly locatable tag; 
         FIGS.  87 A- 87 C  depict another example spring member for attaching to a wirelessly locatable tag; 
         FIGS.  88 A- 88 B  depict another example spring member for attaching to a wirelessly locatable tag; 
         FIGS.  89 A- 89 B  depict another example spring member for attaching to a wirelessly locatable tag; 
         FIGS.  90 A- 90 B  depict another example spring member for attaching to a wirelessly locatable tag; 
         FIGS.  91 A- 91 B  depict another example spring member for attaching to a wirelessly locatable tag; 
         FIGS.  92 A- 92 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIG.  93    depicts another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  94 A- 94 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  95 A- 95 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  96 A- 96 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIG.  97    depicts another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  98 A- 98 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  99 A- 99 C  depict an example cover for a wirelessly locatable tag; 
         FIGS.  100 A- 100 D  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  101 A- 101 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIG.  101 D  depicts another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  102 A- 102 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  103 A- 103 B  depict an example wirelessly locatable tag; 
         FIGS.  104 A- 104 D  depict the tag of  FIGS.  103 A- 103 B  being attached to a tag retainer; 
         FIGS.  105 A- 105 B  depict an example wirelessly locatable tag; 
         FIGS.  105 C- 105 D  depict the tag of  FIGS.  105 A- 105 B  being attached to a tag retainer; 
         FIGS.  106 A- 106 B  depict an example wirelessly locatable tag being attached to a tag retainer; 
         FIGS.  107 A- 107 B  depict an example wirelessly locatable tag; 
         FIGS.  108 A- 108 B  depict the tag of  FIGS.  107 A- 107 B  being attached to a tag retainer; 
         FIGS.  109 A- 109 D  depict an example wirelessly locatable tag and an associated tag retainer; 
         FIG.  110 A- 110 B  depict an example wirelessly locatable tag; 
         FIGS.  111 A- 111 B  depict the tag of  FIGS.  110 A- 110 B  being attached to a tag retainer; 
         FIG.  112 A- 112 B  depict an example wirelessly locatable tag; 
         FIGS.  113 A- 113 B  depict the tag of  FIGS.  112 A- 112 B  being attached to a tag retainer; 
         FIG.  114 A  depicts an example tag retainer for holding a wirelessly locatable tag; 
         FIG.  114 B  depicts the retainer of  FIG.  114 A  being attached to a tag; 
         FIGS.  115 A- 115 C  depict an example wirelessly locatable tag and an associated tag retainer; 
         FIG.  115 D  depicts another example wirelessly locatable tag and an associated tag retainer; 
         FIGS.  116 A- 116 B  depict another example wirelessly locatable tag and an associated tag retainer; 
         FIGS.  117 A- 117 C  depict another example wirelessly locatable tag and an associated tag retainer; 
         FIGS.  118 A- 118 C  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  119 A- 119 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  120 A- 120 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  121 A- 121 B  depict another example tag retainer for holding a wirelessly locatable tag; 
         FIG.  122    depicts another example tag retainer for holding a wirelessly locatable tag; 
         FIGS.  123 A- 125 B  depict example clips for tag holding accessories; 
         FIGS.  126 A- 128    depict example rings for tag holding accessories; 
         FIGS.  129 A- 129 C  depict an accessory for a wirelessly locatable tag; 
         FIGS.  130 A- 130 H  depict example fasteners for an accessory of a wirelessly locatable tag; 
         FIGS.  131 A- 131 H  depict other example fasteners for an accessory of a wirelessly locatable tag; 
         FIGS.  132 A- 132 C  depict other example fasteners for an accessory of a wirelessly locatable tag; 
         FIGS.  133 A- 133 B  depict another example fastener for an accessory of a wirelessly locatable tag; 
         FIGS.  134 A- 134 C  depict an example wireless tag or wireless module that is integrated with an accessory of a device; 
         FIGS.  135 A- 135 C  depict another example wireless tag or wireless module that is integrated with an accessory of a device; 
         FIGS.  136 A- 136 C  depict an example posture-monitoring system having an array of wireless tags; 
         FIGS.  137 A- 137 B  depict wireless tags positioned along a user&#39;s shoulder for monitoring a posture of a user; 
         FIGS.  138 A- 138 B  depict alternative posture-monitoring systems having an array of wireless tags; 
         FIG.  139    depicts an example process for monitoring a user&#39;s posture using an array of wireless tags; 
         FIG.  140    depicts an electronic device locating wirelessly locatable tags in an example environment; 
         FIGS.  141 A- 141 B  depict an electronic device locating wirelessly locatable tags in another example environment; 
         FIG.  142    depicts wirelessly locatable tags attached to a user&#39;s body for monitoring movement or position of the user&#39;s body; 
         FIG.  143    depicts a schematic diagram of an example electronic device; and 
         FIG.  144    depicts a schematic diagram of an example wirelessly locatable tag. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to representative embodiments illustrated in the accompanying drawings. It should be understood that the following description is not intended to limit the embodiments to one preferred embodiment. To the contrary, it is intended to cover alternatives, modifications, and equivalents as can be included within the spirit and scope of the described embodiments as defined by the appended claims. 
     The embodiments herein are generally directed to a device, such as a small, battery-powered tag, puck, or other object of convenient size and shape, that can be physically and/or geographically located using wireless communications systems and techniques. For example, a tag may include an antenna that emits a wireless signal or beacon that is detectable by another electronic device such as a smartphone. Using the detected wireless signal (and using localization techniques such as time of flight, received signal strength indication, triangulation, etc.), the smartphone may be able to determine the position of the tag relative to the smartphone, and, using an absolute location of the smartphone from a GPS, the absolute location of the tag as well. The embodiments herein also relate to the overall network environment that includes (or is defined by) the tags, smartphones, computers, and other devices, and that facilitates the locating of tags as well as numerous other features and functions. 
     Knowing the location of a tag enables a wide range of location-based use cases. For example, the tag may be used to track the location of a portable object such as a set of physical keys, a purse, backpack, article of clothing, or other suitable object or item of personal property. Thus, if the portable object becomes lost or misplaced, a user may be able to find the object using his or her smartphone, tablet, or other suitable device. A tag may also be used to trigger some action on a computing device (e.g., a smartphone) when the device is within a certain proximity and/or orientation relative to the tag. For example, a tag may be positioned in a lobby of a building so that when individuals enter the lobby, their smartphone may detect that it is within a threshold distance of that tag, which in turn causes a map of the building to automatically be displayed on the smartphone. Notably, the devices and techniques described herein allow distance, position, location, and/or orientation determinations with a high degree of accuracy. For example, a smartphone may be capable of determining the location of a tag to an accuracy within three feet, and even to within one foot or less. 
     As described herein, a tag used for tracking physical objects may be a small, conveniently shaped device that can be attached to objects, such as keys, purses, or wallets, to help an owner find lost, misplaced, or stolen objects. The tag may feature a robust structural design that ensures reliable use through a variety of conditions and environments. For example, the tag may be waterproof or at least splash-proof, and may be capable of withstanding impacts, drop events, or other general trauma resulting from normal use of the tag. In part, the ruggedness of the tag may be facilitated by the absence of some types of components, such as glass covers, displays, openings in the housing, external moving parts, and the like. 
     The tag may include a battery, sensors, a wireless communication system, and one or more output devices that can produce audible and/or haptic outputs. Localization functions may be provided by the wireless communication system, and in particular, by the tag sending wireless signals to other devices (e.g., smartphones, tablet computers, etc.) that analyze the wireless signals to determine the distance, position, location, and/or orientation of the tag with a high degree of accuracy. As used herein, localization refers to determining one or more spatial parameters of a tag or other wirelessly locatable device. Spatial parameters include parameters of an object that define an aspect of its distance, position, location, and/or orientation in absolute space or relative to another object. For example, spatial parameters may include parameters such as a distance between objects, a location in a particular geography (e.g., latitude and longitude coordinates), a unit vector pointing from one object to another object, an orientation (also referred to as an angular position or attitude) of an object in three-dimensional space, or the like. 
     The output devices of a tag may also help a user find a lost tag by emitting sounds and/or haptic outputs. The tag may also include input devices that allow users to control or change the tag&#39;s operations. Further, the tag may have a shape and form factor that allows the tag to be easily attached to a user&#39;s property (or to a tag retainer or accessory). 
     As described herein, the tag may operate in any of multiple modes. In a normal operational mode, for example, the tag may conserve power and establish momentary or intermittent communications with one or more other devices (e.g., by sending a wireless beacon signal). The communications may function to confirm the location and may exchange some information about the state or location of the tag. In this way, the tag can essentially periodically update other devices (e.g., a user&#39;s smartphone) with its location and/or status. In some cases, the intermittent communications from the tag may be one-way communications, such as sending a wireless signal for other devices to receive, but not receiving any information from the other devices. 
     The tag may also operate in a lost mode. The lost mode may be triggered in response to an unexpected loss of communication between the tag and one or more other devices (e.g., the user&#39;s smartphone), which may indicate that the tag is no longer in the personal possession or immediate vicinity of the user. The lost mode may also be triggered by a user reporting the tag as lost to a host system or service. As described herein, when the tag is in a lost mode, the tag may be adapted to use third-party devices (e.g., devices of individuals other than the tag&#39;s owner) in order to relay information back to the user. When third-party devices are used to relay information between the tag and a user, the communications may use secured and/or encrypted communications to help ensure the privacy and security of the user. 
     In some cases, third-party devices that are transiently located proximate to the tag may operate as a mesh network or ad-hoc network to relay information back to the user. The information sent to or otherwise made available to the user may include encrypted data that includes an estimated location of the tag and/or one or more of the third-party devices. The secured communications may be decrypted by the user in a way that maintains the anonymity of the various third-party devices, while also allowing the user to locate the tag using the location data generated by the third-party devices. 
     While the foregoing examples primarily describe a tag communicating with a smartphone to allow the smartphone to determine the location of the tag, this is merely one example use case. More broadly, a tag&#39;s position, location, orientation, or other spatial parameter may be determinable by any device that is configured to communicate with the tag. Example devices include smartphones, tablets, laptop computers, wireless routers, desktop computing devices, home automation systems, or the like. In some cases, an environment, such as a user&#39;s home, may include multiple of these devices, and each device may communicate with the tag and determine the tag&#39;s location and/or maintain a record of the tag&#39;s location (or other spatial parameter such as orientation). Moreover, as described herein, these devices may update a server or other database with the tag&#39;s location. This may improve the ability to locate a lost tag, as a user may be able to determine the location of the tag by querying the server or database, even if the user is out of range of the tag. For example, if a user left her keys at home, a desktop computer at the user&#39;s home may have been periodically communicating with (or otherwise receiving signals from) a tag attached to the keys and updating a server with the location of the tag. The user can then simply request the current location of the tag from the server, even if she is miles away and unable to directly communicate with the tag with her smartphone. Further example use cases and device details are described herein. Outside of the user&#39;s home environment, other devices not associated with the user (e.g., other people&#39;s smartphones) may communicate with the tag (or otherwise receive signals from the tag) to securely and anonymously update the server with the location of the tag. For example, outside of the user&#39;s home environment there may be hundreds of thousands or even millions of devices that can securely and anonymously report the locations of tags. Any of these numerous devices that are close enough to a tag to receive signals or communicate with the tag (e.g., via Bluetooth) may securely and anonymously update the server with the tag&#39;s location. In this way, the multitude of devices that can communicate with or receive signals from a tag form a robust, multi-redundant device-location relay network that can continuously (and privately) monitor and update the locations of many individual tags. 
       FIG.  1    depicts an example system that may be used to physically and/or geographically locate a tag  100 . The system may be facilitated in part by a cloud-based service or other host service with which multiple devices communicate to report and receive location information about other devices in the system. The operational links between devices (e.g., wirelessly locatable tags, phones, laptops, tablets, wireless headphones, etc.) and the cloud-based service may allow the system to provide robust localization of devices within the system. For example, devices in the system may be registered with the cloud-based service to allow the devices to communicate with the cloud-based service to both report and receive location data of tags and other devices in the system. Due to the communication and cooperation between and among the various devices in  FIG.  1    to determine the location of tags and devices, the system shown in  FIG.  1    may define and/or be referred to herein as a device-location relay network. 
     Because the device-location relay network facilitates determining the locations of a user&#39;s devices, maintaining security and privacy of the user&#39;s location and other information is of the utmost importance. Accordingly, encryption and anonymization schemes may be used to secure data and prevent access to location data by devices or individuals that are not authorized to do so. In this way, location information may be securely handled by the device-location relay network without exposing location data or other potentially sensitive or private data associated with the various devices in the network. For example, devices, such as smartphones, may execute software that facilitates the sending and receiving of encrypted location reports to and from the cloud-based service, and allows users to see the locations of other devices in the network (if they are authorized to do so). The cloud-based service may also facilitate the passing of encryption keys (e.g., public keys) between various devices to allow users of those devices to securely share their (or their devices&#39;) location without the risk of unauthorized users (including the cloud-service itself) having access to location information of a user&#39;s device. 
     Returning to  FIG.  1   , the tag  100  may be configured to wirelessly communicate with devices  102  (e.g., mobile phones, laptop computers, desktop computers, wireless access points, digital assistants) when the tag is physically proximate to those devices (e.g., within a range of a wireless communication protocol such as ultra-wideband or Bluetooth). The devices  102  may determine the location (and/or other spatial parameter) of the tag  100  and display and/or report the location (and/or other spatial parameter) of the tag to a remote service. 
     One or more of the devices  102  may be associated with the owner of the tag. For example, one or more of the devices  102  may be the tag owner&#39;s phone, digital assistant, laptop or desktop computer, tablet computer, or the like. In such cases, the devices  102  associated with the same user or owner as the tag  100  may directly display the location of the tag  100  to a user. In other cases, such as where the tag  100  (or an object to which the tag is attached) is lost or misplaced outside of the user&#39;s home, the devices  102  may be or include other devices that are not owned or controlled by the user. For example, such devices may include any device that receives signals from the tag or establishes some form of wireless communication with the tag, and can also communicate with a server  104  (or any device associated with a network-accessible service) to report an encrypted, anonymized report that includes the location of the tag. Such devices may include phones, tablet computers, watches, or laptop computers of individuals who have no relationship to the tag&#39;s owner. As used herein, an “owner” of a tag refers to an individual or entity that controls, manages, supervises, operates, leases, owns, or otherwise exercises authority over a tag, and is not necessarily limited to an individual with legal ownership of the tag. 
     The tag itself may not be able to communicate directly to the server  104  to report its location, and indeed, it may not even be aware of its location, as it may lack a GPS or other system for independently determining its own absolute location. Devices that communicate with the tag  100 , however, may be able to communicate to the server  104  to report the location of the tag  100 . For example, devices such as phones, computers, and tablets may communicate with or otherwise detect the presence of a tag, and those devices may report, on an anonymous basis, the tag&#39;s location (and optionally an identifier of the tag and any other information, such as the time) to the server  104  (e.g., via a network  101 ). In addition to devices  102  reporting the locations of tags, the devices  102  themselves may act as tags and report their own locations to the server  104 , and may report the locations of other devices  102  to the server  104  as well. 
     While  FIG.  1    shows a few devices  102  and a single tag  100 , this figure may represent only a small segment of a significantly larger network of tags and devices. Indeed, due to the ubiquity of mobile phones, tablet computers, and the like, the overall device-location relay network may be a dense, ad hoc or mesh-style network that can be used to track the location of many tags and devices. For example, in an urban environment, there may be hundreds of thousands or even millions of devices that can securely and anonymously report the positions and/or locations of tags. In this way, the devices and tags form a robust, multi-redundant device-location relay network that can continuously (and privately) monitor and update the locations of very many devices. 
     In some cases, the devices use their own locations as estimated locations of the tag. For example, if the device is able to connect to the tag via Bluetooth, it may be assumed that the tag is within about 30 feet of the device (or another distance, depending on the parameters of the Bluetooth communication). Thus, for example, the device may report the tag&#39;s location as an area centered about the user&#39;s device and having a radius that corresponds to the estimated range of the wireless communication protocol used to communicate to the tag. In other cases, the device may determine or estimate the location of the tag with greater accuracy. For example, the device may use time of flight (TOF), angle of arrival (AOA), time difference of arrival (TDOA) received signal strength indication (RSSI), triangulation, synthetic aperture, and/or any other suitable technique, to determine a location of the tag relative to the user&#39;s device. These localization techniques may use ultra-wideband signals from the tag, which may allow the device to locate the tag with a high degree of accuracy (e.g., to within one foot of the tag&#39;s actual location). Techniques for determining the spatial parameters of a tag, such as a distance between a tag and another device, a position of the tag relative to another device, a location of the tag, and an orientation of the tag, are described in greater detail with respect to  FIGS.  2 D- 2 E . 
     The location reports sent from the devices that detect the presence of a tag may be encrypted using a public-private key encryption scheme (shown, for example, in  FIGS.  2 A- 2 C ) to ensure that only the owner of a tag can ultimately see the location of the tag. For example, if a tag is lost, devices that happen to be nearby the tag—even if the devices are not associated with the owner of the tag—may detect the tag and receive a public key from the tag ( FIG.  2 B ). A device that detects the tag may query the server  104  to determine if that particular tag has been reported lost. If so (or if the tag and/or device are configured to send encrypted location reports even if the device is not reported as lost), the device may determine a location of the tag, encrypt the location of the tag (and optionally other information) using the public key, and submit the encrypted location report to the server  104  ( FIG.  2 B ). The device may also send information to the tag, such as a message indicating that the tag has been reported as lost. This may cause the tag to change one or more aspects of its operation or to trigger one of multiple operational modes. For example, upon detecting that the tag has been reported lost, the tag may change the frequency that it sends out a beacon (described below), change a message associated with its near-field wireless communications antenna, enter a power-saving mode, or alter some other function or operation of the tag. 
     An owner of the lost tag may query the server  104 , using the public key, for any location reports encrypted using that public key (e.g., via a network  103 , which may be the same network as the network  101  or a different network). If there are location reports associated with the public key, the owner may receive the encrypted location reports and use a private key to decrypt the location reports to determine the location (or estimated location) of the tag ( FIG.  2 C ). The owner may then travel to the location and attempt to locate the tag and any object to which the tag is attached or associated (e.g., a backpack, laptop computer, coat, purse, etc.). 
     The tag may communicate with nearby devices by sending a periodic wireless beacon signal. The wireless beacon signal, which may be transmitted using a Bluetooth communication protocol, ultra-wideband communication protocol, or any other suitable protocol, may be detectable by any device that is monitoring that protocol (e.g., receiving communications via that protocol). The wireless beacon signal, also referred to herein simply as a “beacon signal” or “beacon,” may be transmitted at any suitable frequency, and the particular frequency may depend at least in part on a mode of the tag. For example, when the tag is in an initialization mode or pairing mode, the beacon may be transmitted at a first frequency; when the tag is in a lost mode (e.g., it has been reported to the device-location relay network as being lost, and that status has been provided to the tag), the beacon may be transmitted at a second frequency; and when the tag is in a normal or non-lost mode, the beacon may be transmitted at a third frequency. In some cases, the first frequency is greater than the second frequency, and the second frequency is greater than the third frequency. In other cases, the first and second frequencies are substantially equal, but are greater than the third frequency. As one specific example, the first frequency may be one beacon signal per second (or more frequent), the second frequency may be between one beacon signal per minute and one beacon signal per second, and the third frequency may be one beacon signal per minute (or less frequent). As used herein, a beacon signal may correspond to an advertising packet of a suitable communications protocol, or any other suitable wireless data transmission packet or signal. 
     The beacon may include the public key of the tag and optionally other information such as a tag identifier, a last reported location, a time since a last direct connection to another device, or the like. In some cases, the beacon and the optional additional information are sent to other devices using separate communications channels, protocols, or the like. For example, a tag may send a beacon signal using an ultra-wideband radio and send other information, such as the public key, via Bluetooth. Of course, other assignments of information types to different communications channels or protocols are also possible. 
     The wireless beacon signal may be configured to cause a device to send a location report to the remote server. For example, a tag may transmit a wireless beacon signal to an external device, such as a mobile phone, tablet or laptop computer, or the like. The tag may also transmit a public encryption key to the device. The public encryption key may be included in the beacon signal, or provided to the device from the tag via a different message or communication protocol. In response to receiving the beacon signal, the device may determine a location of the wireless module based at least in part the wireless beacon signal (using localization techniques such as those described herein). The device may prepare an encrypted location report using the public encryption key, where the encrypted location report includes the location of the wireless module, and wirelessly transmit the encrypted location report to a remote server (e.g., the server  104 ). In this way, the tag can cause location reports to be generated on an ongoing basis, such that an accurate, up-to-date location of the tag is available to the tag&#39;s owner. 
     The public-private key encryption scheme may include other techniques to help anonymize the tag and prevent efforts to track individuals or objects. For example, the key pairs may iterate according to an algorithm, such that a tag does not always have the same public key (thus reducing the ability to track a tag by its public key). Alternatively or additionally, the tag may store multiple public keys that can all be decrypted by the same private key, and it can periodically change to a new one of the multiple public keys. 
     As described above, the tag may also include various systems that allow it to be more easily located once the owner is nearby (e.g., within a wireless communication range that allows the tag and another device to communicate, such as 300 feet, 100 feet, 30 feet). For example, the tag may include a speaker or other audible-output system. The owner of the tag may wirelessly command the tag (e.g., via Bluetooth and/or ultra-wideband protocols) to produce an audible output, which the owner can then use to find the tag. As another example, the tag may include an ultra-wideband (UWB) radio, and an owner&#39;s device may also include one or more UWB radios. The owner&#39;s device may be able to use a UWB localization signal emitted by the tag to estimate a position and/or location of the tag and/or guide the owner to the tag. For example, a user interface on the owner&#39;s device may display an arrow or other indicator that points the user towards the location of the tag. The arrow or other indicator may be a live view that continuously updates based on the position of the tag relative to the device, as well as the orientation of the device relative to the tag.  FIGS.  140 - 141 B , below, illustrate example user interfaces that visually direct a user to a tag. 
     Even if the tag is not lost, the device-location relay network may be used to provide other location services. For example, location reports for a tag may be provided by devices in proximity to the tag even when the tag is not lost. In a user&#39;s home, for example, the user&#39;s computer, phone, digital assistant, or any other suitable device(s) may periodically provide, to the server  104 , location reports of the user&#39;s tag(s). Such reports may be used to allow a user to track the locations of his or her objects over time, identify patterns or habits, and the like. Similar location information and/or location reports may also be provided for other devices associated with the user (e.g., the user&#39;s laptop computer, phone, etc.). In this way, locations of many of a user&#39;s devices may be accessible to the user. 
     Localization of user&#39;s devices, such as phones, laptops, etc., may be achieved in various ways. For example, a tag may simply be attached to such devices, thus leveraging the tag&#39;s localization functionality to track the location of the device to which it is attached. Alternatively or additionally, devices may include built-in hardware that provides the same or similar functionality as the tags described herein. Thus, even without an attached external tag, a lost laptop, for example, may use the same or similar systems and leverage the device-location relay network to allow the laptop to be located in the same manner as the tags described herein. Example devices that may include the components and/or provide the functionality of the tags described herein (but without the same physical structure as the tags) include, without limitation, laptop computers, desktop computers, phones (e.g., mobile phones, conventional cordless phones), tablet computers, watches, headphones, wearable electronic devices, computer storage devices (e.g., USB drives, portable hard drives, memory cards, etc.), cameras, remote controls, toys, wireless car keys/key fobs, watches, flashlights, first aid equipment (e.g., automatic electronic defibrillators), cars, motorcycles, smart home devices, head-mounted displays, and computer peripherals (e.g., mice, trackpads, keyboards). 
     Tags may also be configured to interact with devices, such as mobile phones, to cause those devices to take certain actions. For example, a tag may send an instruction, request, or other suitable communication to a device, and in response to receiving the instruction, request, or communication, the device may take an action such as displaying a message on an associated display, sending an encrypted location report, or the like. 
     Tags may trigger remote devices to take various types of actions, and various types of conditions or events may cause the actions to be triggered. In some cases, a determination that a tag is within a threshold distance of a device causes the device to take a certain action. For example, a tag and/or device (e.g., a mobile phone) may cooperate to determine a distance between the tag and device, as described herein. If the distance satisfies a threshold (e.g., if the device is within a threshold distance of the tag), the tag may cause the device to take an action. The particular action that is to be taken by the device may be specified by the tag. For example, in response to the determination that the distance threshold is satisfied, the tag may instruct the device to display a graphical object on the device&#39;s screen. As another example, in response to the determination that the distance threshold is satisfied, the tag may instruct the device to send or relay a message to another device or system. Specifically, the tag may instruct the device to send a location report to a server (e.g., the server  104 ), or to cause a message to be sent to the owner of the tag (e.g., a message indicating that the tag has been found and/or providing a location of the tag). The tag may cause devices to take other kinds of actions as well, as described herein. 
     Instructions sent by a tag to a device may be acted upon by the device, or they may be ignored by the device. For example, a device&#39;s owner may opt-in or opt-out of some or all instructions that originate from tags. Other settings, user preferences, or other criteria may also be used to determine whether a device will respond to or take any actions based on instructions received from a tag. In this way, users can select the degree to which their devices respond to instructions from various tags. In some cases, a user may opt out of all tag-related communications. 
     In cases where the tag triggers a graphical object to be displayed on a device&#39;s screen, the tag may send the content of the graphical object to the device via one of the tag&#39;s available wireless communications systems. More particularly, the tag may store a message in its onboard memory, and when a condition or event is satisfied (e.g., the tag and device are within a threshold distance), the tag may send the message to the device. Upon receiving the message from the tag, the device may display the message on a screen of the device. As a specific example, for a tag that is associated with an object such as a suitcase, the tag may store a message with the request “You are near my suitcase—please return it to the airport lost-and-found for a reward.” The tag may also instruct the device to prompt the device&#39;s user to take a photograph of the lost item (or the location where the tag is estimated to be), and request permission from the device&#39;s user to send the photograph to the tag&#39;s owner (e.g., via the device-location relay network). The tag may also send instructions to the device to cause the device show the location of the item or to display an option to initiate an augmented reality application to assist the user of the device in locating the lost item. As another example, for a tag that is associated with a more static type of object such as a painting in a museum, the tag may store (and send to the device when appropriate) the message “You are near the Mona Lisa—click here for directions to the world&#39;s most famous painting.” The particular content of the message may be customized by an owner or operator of the tag. 
     In other cases, the content of messages may be stored on the device, and the tag may send an identifier of the message to be displayed on the device. For example, the device may store a “lost item” message saying “You are near a lost item—please report to the nearest lost and found,” and the tag may send an instruction indicating that the device should display the “lost item” message. Devices may store multiple messages, and the instructions from the tag may include a unique identifier of the message to be displayed. 
     Tags may be configured to trigger actions on remote devices based on various different conditions or events. In the examples above, the tags cause devices to take actions (e.g., display graphical information, send location reports) based on a device being within a certain proximity of the tag. Other example conditions or events include, for example, a device being beyond a certain distance from a tag, a tag being moved from a stationary position, a battery level of the tag, or the like. 
     Further, the particular actions or events that a tag triggers on other devices, as well as the conditions that cause those actions to be triggered, may depend on a mode of operation or a status of the tag. For example, a tag that is in a “not lost” state or condition may not cause nearby devices to display any information (though they may cause nearby devices to send encrypted location reports). Thus, in response to a determination that the tag is in a first mode (e.g., a “not lost) mode, the tag may not cause an external device to display a message (and may cause it to send encrypted location reports). If that tag is transitioned to a “lost” state or mode, however, the tag may attempt to trigger nearby devices to display a particular message (sent by the tag) to assist in the tag being returned. Thus, in response to a determination that the tag is in a second mode (e.g., a “lost” mode), the tag may cause the external device to display a message and/or perform other possible actions, as described above. Alternatively or additionally, when the tag is in the lost mode it may more frequently instruct remote devices to send location reports. 
     The tag may also be configured to trigger actions on only a subset of devices in its wireless range. For example, a tag may only trigger actions for devices within a certain distance threshold, which may be smaller than the wireless range of the tag. In this way, the tag may instruct actions only on the select few devices that happen to get close enough to the tag to be helpful. As another example, the tag may be limited to a certain number of actions for a given time window. More specifically, a tag may be limited to causing a “lost” message to appear on one device per minute. As yet another example, the tag may be configured to only trigger events on certain types of devices or devices having certain authority. More specifically, a tag may be configured to trigger “lost” messages to appear only on devices that are verifiably controlled by a trusted source (e.g., police, airport employees, friends or relatives of the tag owner, or the like). In some modes of operation, a tag may be configured to trigger certain actions on all device with which it can communicate (e.g., a broadcast). 
     The owner or operator of a tag may select exactly what actions a tag should trigger on nearby devices, as well as the particular conditions that will cause the tag to trigger such actions. The owner or operator may also tie certain actions and conditions to particular modes of the tag (e.g., a “lost” mode, a “not lost” mode, a “lost but do not broadcast location or status” mode, a “low battery” mode). The tag may therefore be highly customizable by the tag&#39;s owner, allowing the tag to perform a variety of possible functions and interact with other devices in various user-selectable ways. 
     Due to the sensitive nature of location information of a user&#39;s possessions, the instant system may use sophisticated encryption and privacy schemes to ensure that unauthorized individuals cannot track the location of another person&#39;s property.  FIGS.  2 A- 2 C  depict an example public-private key encryption system that may be used to ensure the privacy of a user&#39;s location data in the context of a device-location relay network. As shown in  FIG.  2 A , the tag  100  and a user&#39;s smartphone  106  may execute an initialization process in which a public-private key pair is generated or otherwise accessed or obtained. A public key  200  (represented as a lock) may be shared with the tag  100 , and the user&#39;s smartphone  106  may store a private key  202 . 
     Turning to  FIG.  2 B , and as described above, when the tag  100  is deployed to track the location of an object (e.g., a user&#39;s keys), the tag  100  may communicate with other devices  102  to allow the other devices  102  to send encrypted location reports to the server  104 . More particularly, when the tag  100  and another device  102  are in sufficiently close proximity for wireless communications (e.g., via Bluetooth and/or UWB), the tag  100  may communicate the public key  200  to the nearby device  102 . As shown in  FIG.  2 B , three devices  102 - 1 ,  102 - 2 , and  102 - 3  may be close enough to the tag to communicate with the tag  100  (e.g., because a person carrying them walked or travelled nearby the tag  100 ). When the device  102 - 1  communicates with the tag  100 , the tag  100  may provide the device  102 - 1  with the public key  200 . The device  102 - 1  may determine or estimate the location of the tag  100  using the device&#39;s own location (e.g., from a GPS onboard the device  102 - 1 ) and optionally one or more localization techniques that determine a position of the tag  100  relative to the device  102 - 1  (e.g., a distance, azimuth, and elevation from the device  102 - 1  to the tag  100 ). The device  102 - 1  then uses the public key  200  to encrypt the location of the tag  100 , optionally along with other information (e.g., a tag identifier, a time, etc.), into an encrypted location report  204 - 1 . The encrypted location report  204 - 1  is then provided to the server  104  via the network  101 . The devices  102 - 2  and  102 - 3  (as well as additional devices now shown in  FIG.  2 B ) may likewise encrypt location reports  204 - 2 ,  204 - 3 , using the public key  200  received from the tag  100 , and send them to the server  104 . (If the tag  100  is in a location where wireless communication services are unavailable, the device  102  may store the encrypted location reports and upload them to the server  104  once service becomes available.) 
     Because the location reports  204  are encrypted using the public key  200  of a public-private key pair, only an individual or device who possesses the private key  202  can decrypt the location reports  204 , thus helping to maintain the security and privacy of the location of the user&#39;s property. Further, the devices  102  may be configured to perform the reporting functions without alerting a user of the devices  102  that it is occurring. Thus, the device  102  of a person walking past a lost object may send a location report for the lost object without its owner ever knowing that a lost object is nearby. Also, while the devices  102  may be described herein as not associated with the owner of the tag  100 , the same encryption and location reporting techniques may be used even where some or all of the devices  102  are owned or controlled by the owner of the tag  100 . For example,  FIG.  2 B  may represent a user&#39;s home environment, and the devices  102  may be devices within the user&#39;s home. For example, the device  102 - 1  may be the user&#39;s desktop computer, the device  102 - 2  may be a home automation system, and the device  102 - 3  may be a laptop computer. These devices may transmit encrypted location reports  204  to the server  104  so that the user can access the reports to find a lost object in his or her home (or to perform other location-based functions). 
       FIG.  2 C  illustrates how an authorized device (e.g., the device  106 ) may access the location of the tag  100  from the encrypted location reports  204 . In particular, the device  106  may, at the command of a user or automatically based on a triggering event or periodic update, query the server  104  for location reports for the tag  100 . This query may include sending the public key  200  from the device  106  to the server  104 . Notably, the public key  200  may not be capable of decrypting the location reports, but can be used to identify which location reports were encrypted using the public key  200 . 
     In response to a query from the device  106 , and optionally after authenticating that the device  106  is authorized to receive the location reports, the server  104  provides the encrypted location reports  204  to the device  106 . The device may then use the private key  202  to decrypt the location reports  204  and read the reported locations of the tag  100  (e.g., location A, location B, location C). The device  106  may show the reported locations on a map, and may provide directions to the reported locations from the user&#39;s current location. Further, if and when the device  106  is within range of a wireless communication protocol such as UWB, the device  106  may display a direction indicating interface that leads the user directly to the tag  100  (e.g., with a direction indicating arrow overlaid on an image of the real-world environment). An example direction-indicating interface is described herein. 
     Other techniques may also be used to facilitate a user accessing location reports from the server  104 . For example, in some cases, the device  106  may request and/or receive encrypted information from the server  104 , which may include the encrypted location reports  204 , as well as other encrypted location reports (e.g., of other tags), or other encrypted information. Notably, the user will not be able to decrypt location reports or information that was not originally encrypted using the user&#39;s public key, so any encrypted location reports that are not decryptable by the user&#39;s private key remain encrypted and may be discarded by the device  106 . In cases where the device  106  receives more data than just its location reports  204 , the device  106  and/or the server  104  may select the particular information that is sent to the device  106  in various ways. For example, the server  104  may send all of the encrypted location reports that are stored thereon, and any that are not encrypted using the public key  200  may be discarded by the device  106 . In other cases, the server  104  selects a subset of its encrypted location reports to send to the device  106 . For example, the subset may correspond to location reports that were created in a certain time window (e.g., the server  104  may send all encrypted location reports that were sent within 1 hour of when the tag  100  was last in direct peer-to-peer communications with the device  106 ), or the subset may correspond to location reports that were created in certain geographic regions associated with location reports (e.g., the server  104  may send all encrypted location reports that were created in a state or city where the tag  100  was last in direct peer-to-peer communications with the device  106 ). Other criteria or combinations of criteria are also contemplated. 
     As described herein, localization of a wirelessly locatable tag may include the tag sending a signal to another device (e.g., a smartphone), allowing the other device to determine spatial parameters of the tag. Spatial parameters may include distances, orientations, positions, and/or locations. 
     As used herein, “distance” may refer to a measurement of how far apart two points (e.g., electronic devices, other objects, reference points, etc.) are from one another, and may refer to the length of the shortest possible path through space between the two points. 
     As used herein, the term “orientation” may refer to an attitude or angular position of an electronic device (e.g., a tag) relative to another electronic device (e.g., another tag or a smartphone), other point of interest, or reference frame. Orientation may be designated in terms of a rotation about one or more axes required to rotate from a current placement to a reference placement. Example measures of orientation may include Euler angles, Tait-Bryan angles (e.g., yaw, pitch, and roll), orientation vectors, orientation matrices, and the like. 
     As used herein, “position” or “relative position” of an electronic device may refer to the positional relationship of the electronic device in relation to another device, object, or reference point, and may be expressed as the distance between two objects, in combination with a direction vector indicating a direction from one object to another object. 
     As used herein, “location” may refer to a geographical point where an electronic device, other object, or point of interest is positioned, such as a point on the Earth&#39;s surface or elsewhere, and may be designated in terms of a geographic coordinate system (e.g., latitude and longitude) or in terms of a position relative to another geographical point or point of interest. 
     Broadly, wireless signals (e.g., radio frequency signals) sent between two or more electronic devices, may be analyzed to determine spatial parameters. As used herein, “spatial parameters” may refer to information about the placement of an electronic device in the space it occupies. Spatial parameters for an electronic device may include, but are not limited to, any combination of a distance between the electronic device and a point of interest (e.g., another device, an object, a reference point, etc.), an orientation of the electronic device, and a location of the electronic device. As used herein, “localization” may refer to determining one or more spatial parameters of an electronic device. 
     The wireless signals used to determine spatial parameters of electronic devices may include ultra-wideband (UWB) signals. As used herein “UWB signals” may refer to signals transmitted over a large portion of the radio spectrum (e.g., having a bandwidth greater than 500 MHz or greater than 20% of a center carrier frequency). Using UWB signals to perform localization may be referred to herein as “UWB localization.” 
     Electronic devices, such as the wirelessly locatable tags described herein (or other devices that incorporate the functionality of the tags described herein), may be configured as transmitting devices configured to transmit UWB signals, receiving devices configured to detect UWB signals, or both. Each device may include one or more antennas for transmitting and/or detecting UWB signals. A UWB signal transmitted by a transmitting device propagates in all directions or in one or more directions from a transmitting device, and the transmitted signal may be detected by one or more receiving devices. UWB signals used to determine spatial parameters of electronic devices may be sent as pulses. As used herein, a “pulse,” may refer to a rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value. 
     Turning to  FIG.  2 D , as noted above, UWB signals (which may also be referred to herein as beacon signals) may be used to determine a distance D between two electronic devices. In particular, UWB signals may be used to determine a distance between a receiving device (e.g., a smartphone) and a transmitting device  210  (e.g., a tag  100  as described herein). As noted above, a distance between a receiving device and a transmitting device may refer to a measurement of how far apart the receiving device and the transmitting device are from one another, and may refer to the length of the shortest possible path through space between the receiving device and the transmitting device. 
     The receiving device  206   a  (or a device operably coupled to a receiving device) may analyze a UWB signal pulse detected by an antenna  208  of the receiving device  206   a  to determine the distance D between the receiving device  206   a  and a transmitting device  210  that transmitted the UWB signal pulse. In particular, the receiving device  206   a  may determine a time of flight (TOF) of the UWB signal pulse and multiply the TOF by the propagation speed of the signal pulse (e.g., the speed of light) to determine or estimate the distance D between the transmitting device  210  and the receiving device  206   a . As used herein, a UWB signal pulse may be a beacon signal or a portion of a beacon signal. 
     The TOF may be determined by calculating the difference between the transmission time (i.e., the time the signal was transmitted) and the time the signal was detected (also called the time of arrival (TOA)). The transmission time may be included in the detected UWB signal pulse, sent as part of a separate transmission, or known as a result of a previously performed synchronization process between the transmitting device  210  and the receiving device  206   a.    
     Using UWB signals for determining distance may provide numerous advantages, including increased precision in determining TOA and/or TOF. As one example, UWB signals may have shorter wavelengths than other signals, which may reduce the time range in which the signals can be detected. This reduces errors in determining TOA and TOF, which results in more accurate distance estimation. 
     A single signal may be detected by multiple receiving devices and/or multiple antennas of a single receiving device (e.g., a smartphone), and the signal may be used as described above to determine distances between the transmitting device  210  and each receiving device or antennas. Additionally, multiple signals from different transmitting devices (e.g., tags) may be detected by a single receiving device, and the signals may be used as described above to determine distances between the receiving device and each transmitting device. 
     As noted above, UWB signals may be used to determine an orientation of an electronic device relative to a point of interest (e.g., an electronic device, an object, a reference point, etc.). Turning to  FIG.  2 E , UWB signals may be used to determine an orientation of a receiving device  206   b  (e.g., a smartphone) relative to a transmitting device  210  (e.g., tags  100 ). As used herein, the term “orientation” may refer to an attitude or angular position of an electronic device relative to another electronic device, other point of interest, or reference frame. Orientation may be designated in terms of a rotation about one or more axes required to rotate from a current placement to a reference placement. Example measures of orientation may include Euler angles, Tait-Bryan angles (e.g., yaw, pitch, and roll), orientation vectors, orientation matrices, and the like. The orientation of an electronic device relative to a point of interest may also be thought of as a direction to the point of interest with respect to the electronic device. 
     The receiving device  206   b  (or a device operably coupled to a receiving device) may analyze a UWB signal pulse detected by multiple antennas of the receiving device  206   b  to determine an orientation of the receiving device  206   b  relative to a transmitting device  210  (e.g., a tag  100 ) that transmitted the UWB signal pulse. As noted above, receiving devices may include multiple antennas. As one example, as shown in  FIG.  2 E , the receiving device  206   b  may include three or more antennas e.g., antennas  208   a ,  208   b ,  208   c  positioned on or within the receiving device  206   b . The receiving device  206   b  may determine distances d 1 , d 2 , d 3  between each antenna and a transmitting device  210  as set forth above. Differences between the distances d 1 , d 2 , d 3  may indicate the orientation of the receiving device  206   b  relative to a transmitting device. Using the determined distances d 1 , d 2 , d 3  and known separation distances s 1 , s 2 , s 3  between the antennas, a vector V extending from the receiving device  206   b  to the transmitting device  210  may be determined. The vector V may be expressed in terms of a distance between the receiving device  206  and the transmitting device  210  and a direction of the vector V relative to a reference vector of the receiving device  206   b  (e.g., a vector normal to a plane shared by the three antennas or any other vector that is fixed with respect to the three antennas). The direction of the vector V may describe the orientation of the receiving device  206   a  relative to the transmitting device  210 . 
     In some cases, the orientation of the receiving device  206   b  relative to the transmitting device  210  (or vice versa) may be determined independently of determining the distances d 1 , d 2 , d 3 . The receiving device  206   b  may determine a direction from the receiving device  206   b  to the transmitting device  210  (or from the transmitting device  210  to the receiving device  206   b ) by determining a time difference of arrival (TDOA) of the same UWB signal pulse to the three separate antennas  208   a ,  208   b ,  208   c  of the receiving device  206   b . The TDOA for a UWB signal pulse may be determined as the pairwise time difference between the time of arrival of the signal at a first antenna (e.g., antenna  208   a ) and the time of arrival of the signal at a second antenna (e.g., antenna  208   b ). One or more pairwise time differences may be determined, and may be used to determine a direction from the receiving device  206   b  to the transmitting device  210 , which, as noted above, may describe the orientation of the receiving device  206   b  relative to the transmitting device  210 . Other methods for determining direction and orientation may also be used, including triangulation, phase difference of arrival (PDOA), and hybrid TDOA/PDOA methods. 
     The distance between the receiving device  206   b  and the transmitting device  210  and the relative orientation of the receiving device  206   b  may define a position of the receiving  206   b  device relative to the transmitting device  210 . As used herein, “position” or “relative position” of an electronic device may refer to the positional relationship of the electronic device in relation to another device, object, or reference point, and may be expressed as the distance between two objects, in combination with a direction vector indicating a direction from one object to another object (e.g., a distance between a receiving device  206   b  and a transmitting device  210  and a direction vector indicating the direction from the receiving device  206   b  to the transmitting device  210 ). For example, the vector V of  FIG.  2 E  may represent a relative position of the transmitting device  210  and the receiving device  206   b.    
     In various embodiments, information about electronic device(s) (e.g., the spatial parameters discussed above) determined using UWB localization may be combined with other information from a variety of sources to determine spatial parameters. An electronic device may include and/or be operably coupled to one or more sensors or devices for determining spatial parameters or data that may be used to determine spatial parameters. Examples of sensors and devices include magnetometers, gyroscopes, accelerometers, optical sensors, cameras, global positioning system (GPS) receivers, and the like. 
     As one example, an electronic device (e.g., a smartphone) may include or be operably coupled to a GPS receiver configured to determine a location of the electronic device. As noted above, as used herein, “location” may refer to a geographical point where an electronic device is positioned, such as a point on the Earth&#39;s surface or elsewhere, and may be designated in terms of a geographic coordinate system (e.g., latitude and longitude) or in terms of a position relative to another geographical point or point of interest. The position of a transmitting device (e.g., tag) relative to a receiving device may be determined using UWB localization as discussed above. A location of the transmitting device may be determined using a location of the receiving device determined using GPS and the position of the transmitting device relative to the receiving device determined using UWB localization. 
     As another example, an electronic device may include or be operably coupled to a magnetometer or an accelerometer that may be used to determine an orientation of the electronic device relative to the earth. For example, a magnetometer may be used to determine an orientation of the electronic device relative to magnetic north or another known source of magnetic flux. Similarly, an accelerometer may be used to determine an orientation of the electronic device relative to the direction of gravitational acceleration (e.g., inward with respect to the earth&#39;s surface). A direction from the receiving device to the transmitting device relative to the receiving device may be determined using UWB localization as discussed above. The direction from the receiving device to the transmitting device relative to the earth or another known point of interest may be determined by combining the orientation of the electronic device relative to earth determined using a magnetometer or accelerometer with the direction from the receiving device to the transmitting device relative to the receiving device determined using UWB localization. 
     In some cases, the same antenna(s) are used for transmitting and detecting UWB signals. In some cases, the antenna(s) used for transmitting UWB signals are different from the antenna(s) used for detecting UWB signals. The antenna(s) may be operably coupled to one or more transmitters, receivers, processing units, or the like that may be used to generate transmitted signals and/or process detected signals. 
     A location of the transmitting device  210  may also be determined by a receiving device  206   c  by determining the distance between the receiving device  206   c  and the transmitting device  210  when the receiving device  206   c  is at multiple different locations. This process triangulates the location of the transmitting device  210  without using multiple onboard antennas and TDOA analysis of a pulse from the transmitting device  210 .  FIG.  2 F  illustrates how the location of the transmitting device  210  is determined using this technique (which may be referred to as synthetic aperture). 
     As described above, the transmitting device  210  may emit a pulse (e.g., a UWB signal pulse) that is detectable by an antenna  208   d , and the receiving device  206   c  may analyze the pulse (e.g., using TOF) to determine the distance from the receiving device  206   c  to the transmitting device  210 . As shown in  FIG.  2 F , in order to determine the location of the transmitting device, the receiving device  206   c  may determine multiple distances (e.g., distances d 4 , d 5 , and d 6 ) to the transmitting device  210  when the receiving device  206   c  is at multiple locations (e.g., L 1 , L 2 , and L 3 ). Because the location of the receiving device  206   c  at locations L 1 , L 2 , and L 3  is known (as determined by an onboard GPS, accelerometer(s), and/or other positioning systems) and the distances between the receiving device  206   c  and the transmitting device  210  are also known, the receiving device  206   c  can determine, using triangulation, the location L 4  of the transmitting device  210 . Further, using an onboard magnetometer, accelerometer, and/or other systems, the receiving device  206   c  can determine its orientation relative to the determined location of the transmitting device  210 . The orientation of the receiving device  206   c  relative to the transmitting device  210  together with the location of the transmitting device  210  provides a full complement of spatial parameters of the transmitting device  210  to facilitate the functionalities described herein. 
     With reference to the process described in  FIG.  2 F , the transmitting device&#39;s location may be determined once the receiving device  206   c  determines at least three distance measurements between the receiving device  206   c  and the transmitting device  210 . In some cases, once the location of the transmitting device  210  is established using at least three distance measurements, the receiving device  206   c  may perform more distance measurements at additional locations of the receiving device  206   c . These subsequent measurements may be used to refine and/or update the determined location of the transmitting device  210 , or otherwise to improve the accuracy of the location determination. 
     As noted above, a wirelessly locatable tag may take the form of a small device that can be easily attached to objects such as keys, backpacks, purses, and the like. Broadly, the tag may have a small size (e.g., having a diameter less than about 3 inches, less than about 2 inches, less than about 1 inch) that is rugged, water resistant (e.g., IP66, IP67, or IP68, according to international ingress protection standards), and portable. The tag may also have acoustic and haptic output systems, and optionally an input system (e.g., a button-like input). The tag may also include a battery that can be easily and conveniently replaced, and may be sealed against water, dust, and other contaminants. 
       FIGS.  3 A- 3 C  depict an example wirelessly locatable tag  300  in accordance with the ideas described herein. The tag  300  may be an embodiment of the tag  100 , and may include any or all of the components and may provide any or all of the functionality of the tag  100  (or any other wirelessly locatable tag or device described herein). For brevity such details may not be repeated here. 
       FIG.  3 A  depicts a top view of the tag  300 ,  FIG.  3 B  depicts a side view of the tag  300  of  FIG.  3 A , and  FIG.  3 C  depicts a side exploded view of the tag  300 . As shown in  FIG.  3 C , the tag  300  may include main body portion  302 , a removable bottom housing member  304 , and a removable and/or replaceable battery  306 . The bottom housing member  304 , which may also be referred to as a battery door or battery cover, may be removed by pressing on the bottom housing member  304  and twisting it relative to the main body portion  302 , thereby disengaging one or more latches, clips, arms, or other mechanisms that hold the bottom housing member  304  to the main body portion  302 . Various configurations of housing members and engagement mechanisms may be used to allow access to a battery cavity of the tag  300  so that a battery can be removed and replaced, while also ensuring that the battery cavity remains safely secured and sealed against ingress of debris, water, or other contaminants. Additional example configurations for securing housing members are described herein. Together, the top and bottom housing members may define (or at least partially define) a housing of a tag (which may also be referred to as an enclosure). 
     The tag  300  may also define a housing gap  301  that facilitates attaching and retaining the tag  300  directly to other objects, such as backpacks, wallets, and purses, and/or to dedicated accessories that are adapted to receive the tag  300 . The housing gap  301  may be a gap or channel defined between the main body portion  302  and the bottom housing member (battery door)  304 . The housing gap  301  may extend around a complete circumference of the tag  300 , or it may extend only partially around the tag  300 . Where a tag has a shape other than a circular shape, such as a square shape, those tags may have a housing gap similar in appearance and/or function to the housing gap  301  to facilitate attachment to accessories. Housing gaps may also be formed between housing members other than the main body portion and bottom housing member, as described herein. In some cases, a housing gap may be defined by a single housing member (e.g., a groove or recess formed into a main body portion). Accessories for attaching to a tag, and for attaching the tag to other objects, may include, for example, straps, key fobs, lanyards, belts, luggage tags, and the like. Some example accessories are described herein with respect to  FIGS.  69 A- 128   . 
       FIG.  4    depicts a cross-sectional view of an example wirelessly locatable tag  400 . The tag  400  may be an embodiment of the tag  100  or the tag  300 , and may include any or all of the components and may provide any or all of the functionality of the tag  100  (or any other wirelessly locatable tag or device described herein). An example of the various hardware elements that may be included in the tag  400  is described below with respect to  FIG.  144   . For brevity such details may not be repeated here. 
     The tag  400  includes a top housing member  402 , an audio system  404 , an antenna assembly  406 , a circuit board  408 , a frame member  410 , a battery  416 , and a bottom housing member  412  (which may also be referred to as a battery door). The top housing member  402 , audio system  404 , antenna assembly  406 , circuit board  408 , and frame member  410  may all be part of or define a main body portion, such as the main body portion  302  ( FIGS.  3 A- 3 C ). 
     The top housing member  402  may define a top exterior surface of the tag  400  and an interior surface opposite the top exterior surface. The top housing member  402  may also define some or all of a side exterior surface of the tag  400 , where the side exterior surface extends around a periphery of the top exterior surface (as shown in greater detail with respect to  FIGS.  3 A- 3 B ). The bottom housing member  412 , which may also operate as and be referred to as a battery door, may define a bottom exterior surface of the tag  400 . As shown, the bottom housing member  412  also defines part of the exterior side surface. The top and bottom housing members  402 ,  412  may engage one another to define substantially the entire exterior surface of the tag  400 , and may define a substantially waterproof seal between the top and bottom housing members  402 ,  412 . The top and bottom housing members  402 ,  412  may also define an interior volume of the tag  400 . 
     The audio system  404  may be configured to produce audio outputs that can be used to help a user locate the tag  400 . For example, when a user is attempting to locate a lost tag  400  (and thus locate any object attached to or associated with the lost tag), the user may use a smartphone to wirelessly command the tag  400  to produce an audible sound such as a beeping or other audible tone (e.g., constant tone, song, etc.). The user can then attempt to find the tag  400  by listening for the audible sound. The audio system  404  may be any suitable component or system for producing sound, such as a voice coil speaker, a piezoelectric speaker, or the like. Example audio systems are described herein. 
     In some cases, the audio system  404  produces audio outputs by moving a portion of the top housing member  402  like a diaphragm or cone of a speaker. For example, the audio system  404  or a portion thereof may be attached to the inside surface of the top housing member  402  to directly apply forces on the top housing member  402  that cause the top housing member  402  to flex, deform, or otherwise move to produce audio output. To facilitate movement of the top housing member  402 , the top housing member  402  may have a movable area or portion that is not fixed to other components of the tag  400  or is not otherwise immobilized. The movable area may be configured to allow or facilitate audio output in the range of about 100 Hz to about 10000 Hz. The audio system  404  may also be configured to produce haptic or tactile outputs by moving the movable area of the top housing member  402 . More particularly, because the audio system  404  can move the top housing member  402  to produce audio, the audio system  404  may be operated to produce a haptic or tactile output that a user can feel with his or her hand or other body part. In some cases, haptic or tactile responses may be different from audible outputs, though haptic outputs may also be audible, and audible outputs may be accompanied by tactilely detectable vibrations. 
     The antenna assembly  406  of the tag  400  may have one or more antennas attached to or otherwise integrated with an antenna frame of the antenna assembly  406 . For example, the antenna assembly  406  may include separate (and/or shared) antennas for near-field wireless communications protocols (e.g., ISO/IEC 14443, ISO/IEC 18092, ISO/IEC 21481), UWB protocols, Bluetooth (e.g., IEEE 802.15), WiFi (e.g., IEEE 802.11), cellular protocols, or the like. In some cases, some or all of the antennas are integral to the antenna frame of the antenna assembly  406  (e.g., a single, monolithic antenna frame component). For example, antennas may be insert molded with the material of the antenna frame of the antenna assembly  406  such that the antennas are at least partially embedded in the material of the antenna frame. In other cases, antenna material (e.g., metal) may be formed and/or applied using laser direct structuring, whereby a laser beam is directed onto the material of the antenna frame to form a region that is then metallized using a plating (e.g., electroplating) or other deposition operation. Other techniques for attaching or forming antennas onto the antenna assembly  406  may also be used. The antenna frame of the antenna assembly  406  may be formed of or include a glass-fiber reinforced polymer or any other suitable material. 
     The circuit board  408  may include a substrate and may include processors, memory, and other circuit elements that generally perform the electrical and/or computational functions of the tag  400 . The circuit board  408  may also include conductors and/or electrical interconnects that electrically couple the various electrical components of the tag  400 . The circuit board  408  may also include or be coupled to a battery connector that contacts a battery or other power source for the tag  400 . The circuit board  408  may be attached to the antenna assembly  406  and/or the frame member  410  of the tag  400 . 
     The frame member  410  may act as a support structure to which other components of the tag  400  are attached. For example, the top housing member  402 , the antenna assembly  406 , the audio system  404 , the circuit board  408 , and the bottom housing member  412  may all be secured to the frame member  410 . Accordingly, loads imparted to the device via these components may be fully or partially transferred to the frame member  410 . The frame member  410  may also define a battery recess that is configured to receive, support, and align the battery  416  inside the housing of the tag  400 . The frame member  410  may be formed of or include a tough, rigid material such as a polymer, fiber-reinforced polymer, metal, ceramic, or the like. 
     The particular configurations, positions, shapes, and integration details of the components in  FIG.  4    represent one example embodiment of a tag. It will be understood that other embodiments of tags may have configurations, positions, shapes, and integration details that differ from what is shown in  FIG.  4    while still providing the same or similar functions as the tag  400 . 
       FIG.  5 A  depicts an example wirelessly locatable tag  500 , and  FIG.  5 B  depicts a cross-sectional view of the tag  500  as viewed along line A-A in  FIG.  5 A . The tag  500  may be an embodiment of the tag  100 , and may include any or all of the components and may provide any or all of the functionality of the tag  100  (or any other wirelessly locatable tag or device described herein). An example of the various hardware elements that may be included in the tag  500  is described below with respect to  FIG.  144   . For brevity such details may not be repeated here. 
     As shown in  FIG.  5 B , the tag  500  includes a top housing member  502  (also referred to herein as an upper housing member) and a bottom housing member  516  (also referred to herein as a lower housing member), which together may form at least part of an enclosure of the tag. The top and bottom housing members  502 ,  516  may enclose or house components of the tag  500 , as described herein. 
     The top housing member  502  may define a top exterior surface  501  of the tag  500 . The top exterior surface  501  of the tag  500  may be an unbroken, seamless surface. For example, the entire top exterior surface  501  of the tag  500  may be defined by a single, unitary piece of material (uninterrupted by displays, buttons, openings, additional housing components, or the like). Accordingly, the top housing member  502  may define an entirety of the top exterior surface of the tag  500 , and may be defined by a unitary structure (e.g., a unitary or single-piece polymer structure). The top housing member  502  may also define a peripheral side wall  519  defining a peripheral side surface of the tag  500 . 
     Further, as described herein, a portion of the top housing member  502  that defines the top exterior surface  501  may act as a diaphragm of an audio system that produces audible and/or haptic outputs. For example, an audio system may move a portion of the top housing member  502  so that the moved portion of the top housing member  502  produces the pressure waves that correspond to the audible output. As noted above, the motion of the top housing member  502  may also be used to produce haptic outputs. 
     In some cases, substantially the entire exterior of the tag  500  may be defined by two components, the top housing member  502  and the bottom housing member  516 . In such cases, the tag  500  may lack features such as displays (and associated housing components such as transparent covers), speaker/microphone openings, buttons, lenses, light sources, and the like. While some tag embodiments may include such components, embodiments that lack them may have better environmental sealing and energy efficiency, may be cheaper to manufacture, and may be simpler to use as compared to devices that include such features or components. 
     The top exterior surface  501  may also define some or all of a side exterior surface  503  that extends around a periphery of the top exterior surface  501 . The side exterior surface  503  may have any suitable shape or profile, such as a continuously curved profile (in cross-section), or a curved portion.  FIGS.  5 A- 5 B  illustrate an embodiment in which at least a portion of the top exterior surface  501  is curved (e.g., the portion that is proximate an edge where the top exterior surface  501  meets the side exterior surface  503 ).  FIGS.  5 A- 5 B  illustrate an embodiment in which the side exterior surface  503  has a cross-sectional shape with a flat side. The bottom housing member  516  may define a bottom exterior surface  505  of the tag  500 . The bottom housing member  516  may be removable from the remainder of the tag  500  to facilitate removal and replacement of a battery  514 . The bottom housing member  516  may also be referred to as a battery door. The battery  514  may be any suitable type of battery, such as a button cell battery. 
     The tag  500  may also include an antenna assembly  508 . The antenna assembly  508  may have one or more antennas attached to or otherwise integrated therewith. For example, the antenna assembly  508  may include separate (and/or shared) antennas for near-field wireless communications protocols, UWB protocols, Bluetooth, WiFi, cellular protocols, or the like. In some cases, some or all of the antennas are integral to the antenna frame of the antenna assembly. Additional details of antenna assemblies and associated antennas are described herein. 
     The antenna assembly  508  may act as a structural support for at least a portion of the top housing member  502 . For example, a support portion  511  of the antenna assembly  508  (which may be considered a portion or surface of a peripheral support flange  523 ) may contact a portion of an interior surface of the top housing member  502 . In some cases, the support portion  511  of the antenna assembly  508  may be attached to the bottom or inner surface of the top housing member  502  using adhesive, fasteners, mechanical features, or any other suitable mechanism. In other cases, the support portion  511  contacts but is not bonded to the top housing member  502 . The support portion  511  may extend completely around the antenna assembly  508 , defining a continuous, ring-shaped support portion  511  that defines an upper-most (e.g., top) surface of the antenna assembly  508 . In other implementations the support portion  511  may include multiple non-continuous segments that extend from the antenna assembly  508  to contact the top housing member  502 . 
     At least a portion of the top housing member  502  may be set apart from the antenna assembly  508  by a gap, such as the gap  509 . The gap  509  may be defined in part by the support portion  511 . More specifically, the gap  509  may be defined at least in part by a portion of the antenna assembly  508  that is recessed relative to the top surface of the support portion  511 . 
     The gap  509  may allow the portion of the top housing member  502  to be moved to produce haptic and audio outputs without the antenna assembly  508  interfering with the audible or haptic output. In some cases, the size of the gap is greater than a maximum target deflection of the top housing member  502  during audible and/or haptic outputs. Thus, for example, if the tag  500  is configured to produce audio and/or haptic outputs having a certain characteristic (e.g., a maximum or target amplitude, volume, frequency, or other property), the size of the gap  509  may be selected to be greater than the deflection of the top housing member  502  that results from those audible and/or haptic outputs. In some cases, the maximum size of the gap  509  (e.g., the distance between the topmost surface of the antenna assembly  508  and the bottom surface of the top housing member  502 ) may be less than or equal to about 500 microns, 400 microns, 300 microns, 200 microns, 100 microns, 50 microns. 
     The antenna assembly  508  may also act as a structural support for the tag  500  and the components within the tag  500 . More particularly, the antenna assembly  508  may be formed of materials, have a particular shape, and interact with other structural components to define a main load-bearing structure of the tag  500 . For example, the tag  500  may include components that may be sensitive to loads, deflection, movement, shock, or the like. Such components may include a circuit board  510 , solder joints between the circuit board  510  and other components (e.g., antennas, battery contacts, speakers and/or audio systems, sensors, haptic actuators, or the like). Such components may be relatively delicate, and may not be structurally capable of withstanding direct applications of forces from normal use of the tag  500  (including, for example, drops, impacts, or the like that may occur during normal use). In order to protect these components, they may be coupled to and/or protected by the antenna assembly  508 , alone or in conjunction with other components of the device. 
     For example, as shown in  FIG.  5 B , the circuit board  510  may be mounted to or otherwise in contact with the antenna assembly  508 , and may be mounted such that it does not contact either the top or bottom housing members  502 ,  516 , thereby isolating the circuit board  510  from direct force application via the top or bottom housing members  502 ,  516  (e.g., from the tag  500  being dropped, squeezed, impacted, or the like). The circuit board  510  may be mounted to the antenna assembly  508  using an adhesive (e.g., temperature sensitive adhesive, heat sensitive adhesive), fasteners, clips, heat stakes, rivets, or any other suitable mechanism or technique. 
     The antenna assembly  508  (e.g., a peripheral support flange  523  of the antenna assembly  508 ) contacts a frame member  512  at an interface  521  and defines a recessed region or cavity on one side of the antenna assembly  508  in which the circuit board  510  may be positioned. The peripheral support flange  523  may at least partially surround an outer periphery of the circuit board  510 , as shown in  FIG.  5 B . The recessed region or cavity of the antenna assembly  508  (which may be surround or defined at least in part by the peripheral support flange  523 ) may be referred to herein as a circuit board cavity. 
     The peripheral support flange  523 , through the interface  521 , defines a load path from the antenna assembly  508  to the frame member  512 . In this way, forces applied to the tag  500  may be directed through the antenna assembly  508  and the frame member  512  and not applied to the circuit board  510 . More broadly, the antenna assembly  508  (and in particular the top wall of the antenna assembly  508  and the peripheral support flange  523 ) may form a protective support and/or partial shell around the circuit board  510 . As one specific example, if a force is applied to the top exterior surface  501  of the tag  500  (e.g., while the bottom exterior surface  505  is on a table or other surface), the force may be directed through the top housing member  502 , through the antenna assembly  508  (e.g., the peripheral support flange  523 ), through the frame member  512 , and into the bottom housing member  516 . In this way, the force may be directed around the circuit board  510  to reduce or eliminate any deflection or deformation of the circuit board  510  or its components or connections. Further, the peripheral support flange  523  may be attached to the frame member  512  at the interface  521  (as well as at other interfaces), thereby defining an at least partially enclosed volume in which the circuit board  510  (among other possible components) is positioned. Such interfaces may be sealed with sealing members, adhesives, glue, O-rings, or other components, thereby sealing the at least partially enclosed volume along those interfaces. 
       FIG.  5 B  also depicts an audio system that includes a coil  504  coupled to a top housing member  502 . The coil  504  may be proximate a magnet assembly  506 . When a signal is applied to the coil  504  (which is in a magnetic field produced by the magnet assembly  506 ), Lorentz forces may be produced which, in turn, cause the top housing member  502  to move, oscillate, vibrate, or otherwise produce an audible and optionally tactile output. In some cases, the top housing member  502  locally deflects or deforms to produce the audible and/or tactile output. Appropriate clearances may be provided between the top housing member  502  and an antenna assembly  508  to allow the top housing member  502  to move a distance and in a manner that is sufficient to produce the target audio and/or tactile output, as described above. Other types of audio systems may be used instead of or in addition to the audio system shown in  FIGS.  5 A- 5 B , such as piezoelectric elements, a ported speaker module, or the like. 
     The tag  500  may also include a hard-stop  520 , or travel limiting member, that limits deflection of the top housing member  502 . The hard-stop  520  may reduce the perception of flexibility of the top housing member  502  by limiting the distance that the top housing member  502  can move when pressed by a user. In particular, while movement of the top housing member  502  may be necessary for producing audible and haptic outputs, and optionally to detect inputs, the flexibility of the top housing member  502  that is necessary to facilitate such outputs and inputs may decrease the physical sensation of quality and structural integrity of the tag  500  as a whole. By limiting the distance that the top housing member  502  can move towards the antenna assembly  508  below a threshold, users may not tactilely perceive the flexibility of the top housing member  502  to the extent that they would if the top housing member  502  were not so limited. Accordingly, the maximum distance of the gap between the topmost surface of the hard-stop  520  and the bottom surface of the top housing member  502  may be less than or equal to about 500 microns, 400 microns, 300 microns, 200 microns, 100 microns, or 50 microns. This distance may be sufficient to allow the audio system (which includes and/or is defined by the coil  504  and the magnet assembly  506 ) to produce audible and/or haptic outputs, as well as to allow the detection of inputs, while also providing a tactile sensation that the top housing member  502  is rigid or substantially non-movable. 
     In some cases, the audio system may act as an input system (e.g., a button) in addition to acting as an audible and haptic output system. For example, deflections of the top housing member  502  (above the coil  504  and magnet assembly  506 ) may result in movement of the coil  504  in the magnetic field of the magnet assembly  506 , thereby causing a detectable current to flow in the coil. This may be used to trigger the tag  500  to take some action (e.g., enter an initialization mode, cease an audio output, enter a “found” mode, etc.). In some cases, a separate sensor or switch (e.g., a force sensor, a dome switch) may be used to detect inputs to the device. For example, a sensor or switch may detect deflection or deformation of the top housing member  502  as a result of a user pressing on or squeezing the tag. The gap between the hard-stop  520  and the bottom surface of the top housing member  502  may be sufficient to facilitate the detection of an input force applied to the top housing member  502 . Where a dome switch or other type of mechanical or electromechanical switch component is used (instead of or in addition to using an audio system as an input system), it may be positioned between the top housing member  502  and an underlying frame member, or in any suitable gap (between any two components) that can be reduced in size by a user to provide an input. 
     Wirelessly locatable tags may also use other types of input devices or systems to detect user inputs. For example, tags may include accelerometers or other motion-sensing systems. In such cases, users can move or manipulate the tags in certain ways to provide inputs to the tags, such as shaking the tag, tapping the tag, sliding the tag, or the like. The tag may be configured to respond to individual instances of such motions (e.g., a single tap or a single shake), or to particular patterns of motions (e.g., multiple taps within a predetermined time window, a tap followed by a shake followed by another tap). 
     As another example, the tag may include movable components or members (other than or in addition to a deformable top housing member, as described above) that can be manipulated (e.g., pushed, squeezed, pressed) by a user to provide an input. For example, the tag may include a mechanical button that can be pressed to provide an input. As another example, a battery door may be movable such that a user can push the battery door like a button. The battery door may be biased in an undepressed position by a spring member, and a sensor may determine when the battery door is depressed. The biasing and sensing functions may be provided by any suitable mechanisms. For example, dome switches (e.g., tactile dome switches) may be used to provide both biasing and sensing functions to the battery door. In other cases, a spring may act as a biasing member, and sensing functions may be provided by optical sensors, capacitive sensors, Hall effect sensors, or the like. The biasing force that maintains the battery door in an undepressed position may be provided by a compliant member that also biases a battery into a battery cavity of a tag, such as the compliant member  518  (described herein). 
     Tags may also include force sensors that detect an input upon detecting a force, applied to an exterior surface of the tag, that satisfies a threshold force. For example, a force sensor may be positioned between two components (e.g., a top housing member and a frame member, a bottom housing member and a battery, etc.), and a squeezing or pressing force applied to the tag may deform the tag and thus the force sensor. When the tag detects a threshold level of force, it may register the force as an input to the tag. 
     Upon detecting an input to the tag, via the input described herein or any other suitable input mechanism, the tag may perform some action. For example, upon detecting an input, the tag may enter an initialization mode or begin an initialization process. As another example, upon detecting an input, the tag may change from a “lost” operating mode to a “found” operating mode (which may include changing a beacon frequency, as described herein, causing a message to be sent to a host service updating a status of the tag to “found”, or the like). As yet another example, upon detecting the input, the tag may produce an output that provides some information about the device (e.g., an audible tone or visual output indicating information such as a battery charge state). As yet another example, upon detecting the input, the tag may produce an audio output (or if the tag has a display, a graphical output) providing instructions on how the tag is to be handled if found (e.g., “please call owner at this number” or “please contact police”). Other types of actions in response to detecting an input are also contemplated. 
     As noted above, the tag  500  includes a circuit board  510 . The circuit board  510  may include a substrate (e.g., a printed circuit board substrate) with electrical components coupled thereto. Example electrical components include, for example, processors, memory, sensors (e.g., temperature sensors, accelerometers, magnetometers, gyroscopes, optical sensors, microphones, pressure sensors, barometric sensors, or the like), conductive elements (e.g., conductive traces), and the like. A battery connector may be conductively coupled to the circuit board  510  and configured to conductively couple to a battery of the tag  500  to provide electrical power to the electronic components of the tag  500 . 
     The bottom housing member  516  may be removable from the top housing member  502  to facilitate removal and replacement of the battery  514 . The bottom housing member  516  may be removably coupled to the tag via a latching or other engagement system that prevents or inhibits unintentional removal of the bottom housing member  516 . For example, in order to ensure that the battery  514  does not unintentionally fall out of the tag  500  and is not easily accessible to children, the bottom housing member  516  may require a press-and-twist motion, as described with respect to  FIGS.  3 A- 3 C . Various example mechanisms for securing the bottom housing member  516  (also referred to as a battery door) to the tag  500  are described herein with reference to  FIGS.  12 A- 12 C and  14 A- 25 C . The bottom housing member  516  may be removably coupled to the tag  500  by engaging with latching features of the top housing member  502 , a frame member  512 , or any other suitable component(s) of the tag  500 . 
     The tag  500  may also include a compliant member  518  between the bottom housing member  516  and the battery  514  to bias the battery  514  into the battery cavity of the tag  500  and against the battery connector that electrically couples the battery  514  to the electrical components of the tag  500 . The compliant member  518  may be or may include a spring (e.g., a leaf spring, a coil spring), a polymer (e.g., a foam or elastomer pad), or any other suitable compliant member that biases the battery towards the tag  500 . The compliant member  518  may also help latch or otherwise bias the bottom housing member  516  in a locked or engaged state (e.g., by forcing the latch member against or otherwise into engagement with an engagement feature). For example, as described herein, the bottom housing member  516  and the frame member  512  may include complementary engagement features, and the compliant member  518  may bias the engagement features against and/or into engagement with each other in a manner that prevents or limits removal of the bottom housing member  516  (at least without manipulating the bottom housing member  516  in a specific manner. 
       FIG.  6    depicts an exploded view of the tag  500 , showing another view of the components of the tag  500  and their arrangement. As shown in  FIG.  6   , the frame member  512  may include latch members  600  that engage the antenna assembly  508  to retain the frame member  512  to the antenna assembly  508 . In some cases, the latch members  600  are positioned on the antenna assembly  508  and engage the frame member  512 . The bottom housing member  516  may also include latch members  602  that engage the frame member  512  to removably couple the bottom housing member  516  to the frame member  512 . The configurations and locations of the latch members  600  and  602  in  FIG.  6    are merely examples, and other configurations and locations are also contemplated. 
       FIG.  7    depicts a detail view of a portion of the wirelessly locatable tag  500 , corresponding to detail A-A in  FIG.  5 B .  FIG.  7    shows interfaces between the top housing member  502 , the bottom housing member  516 , and the frame member  512 . A first sealing member  702  may seal a joint or interface between the top housing member  502  and the frame member  512 . A second sealing member  708  may seal a joint or interface between the bottom housing member  516  and the frame member  512 . The first and second sealing members  702 ,  708  may be defined by different segments of a single piece of material that is co-molded or insert molded onto the frame member  512 . In such cases, the first and second sealing members  702 ,  708  may be connected by a bridge segment that extends from the first sealing member  702  to the second sealing member  708 . The bridge segment may be positioned in a channel along an interior side of the frame member  512  such that the bridge segment is not exposed along the exterior of the tag  500 . In other example implementations, the first and second sealing members  702 ,  708  may be separate from one another (e.g., not joined by a bridge segment). 
     The first and second sealing members  702 ,  708  may form a substantially waterproof seal between the components with which they interface. The first and second sealing members  702 ,  708  may be formed from or include any suitable material, such as a compliant polymer material (e.g., an elastomer or foam). As noted, the first and second sealing members  702 ,  708  may be molded against the frame member  512  such that both the first and second sealing members  702 ,  708  bond to or are otherwise affixed to the frame member  512 . In other cases, the first and second sealing members  702 ,  708  are molded or formed separately from the frame member  512  and then attached to the frame member  512  using an adhesive, ultrasonic welding, or any other suitable technique. 
     The top housing member  502  and the frame member  512  may be configured to remain attached to one another during normal operations (e.g., they may not be removably coupled, and detaching them from one another may damage the top housing member  502 , the frame member  512 , or both). Accordingly, the first sealing member  702  need not be configured to allow motion between the top housing member  502  and the frame member  512 . By contrast, the bottom housing member  516  may be configured to be detached from the frame member  512  to provide access to the battery cavity (e.g., for replacing the battery). Accordingly, the second sealing member  708  may include a projecting portion  706  that is configured to contact and slide along a surface of the bottom housing member  516  when the bottom housing member  516  is attached to and detached from the frame member  512 . The projecting portion  706  may have a triangular cross section that tapers or narrows along the length of the projecting portion  706  towards the free end. This shape may reduce the amount of force required to compress the second sealing member  708  (as compared to other shapes, such as circular cross-sectional shapes), thereby forming a waterproof seal while producing less force on the bottom housing member  516  during attachment and detachment than a differently shaped sealing member (e.g., one with a circular cross-section). 
     The tag  500  may also include a barometric vent to allow air to pass into and out of the tag  500  to allow pressure equalization between the ambient environment and the internal volume within the tag  500  (and to allow an optional barometric sensor or pressure sensor within the tag  500  to be exposed to the ambient pressure conditions exterior to the tag  500 ). The barometric vent may include or be defined by a passage  704  (or opening) that fluidly couples the external or ambient environment around the tag  500  to the internal volume of the tag  500 , as well as a waterproof, air-permeable membrane  712  to prevent water ingress through the barometric vent while still allowing air to pass through to allow pressure equalization. The air-permeable membrane  712  may be positioned between a surface of the bottom housing member  516  and a flange portion  714  of the compliant member  518 . The flange portion  714  may help to hold the membrane  712  in position and prevent it from moving or detaching when air or water pressure is applied to the membrane  712 . The flange portion  714  may define an opening  710  that aligns with the passage  704  or is otherwise configured to allow air to pass through to facilitate pressure equalization. As shown, the flange portion  714  is an integral part of the compliant member  518  (which may be a unitary metal member), though in other implementations the flange portion  714  may be replaced with another bracket, backing, plate, or other component. The barometric vent may also include other components such as screens, additional membranes, fasteners, adhesives, and the like. 
     The barometric vent fluidly couples the ambient environment of the tag  500  with the battery cavity of the tag  500 . The battery cavity may be fluidly coupled to the rest of the internal volume of the tag  500  such that the barometric vent is sufficient to allow pressure equalization between the ambient environment and the entire (or substantially entire) internal volume of the tag  500 . In some cases, the frame member  512  defines openings for contacts of a battery connector to extend into the battery cavity from another area of the internal volume, and these openings may also allow air flow between the battery cavity and other internal areas of the tag  500 . In this way, only one barometric vent is necessary to allow pressure equalization to the entire tag  500 . 
     As described elsewhere herein, the bottom housing member  516  may define a flange or lip  716  that extends circumferentially around the bottom housing member  516  and defines one side of a housing gap  718 . (The frame member  512  may define an opposite side of the housing gap  718 ). The flange or lip  716 , and the housing gap  718  more generally, may be used to attach the tag  500  to an accessory, as described herein with respect to  FIGS.  69 A- 128   , for example. 
       FIG.  8 A  depicts the antenna assembly  508  of the tag  500 . The antenna assembly  508  may include one or more antennas  804 ,  806 ,  808  embedded in or otherwise attached to an antenna frame  802 . The antenna frame  802  may be a polymer (e.g., a liquid crystal polymer, fiber-reinforced polymer) or any other suitable material, and the antennas  804 ,  806 ,  808  may be metal (or another suitable conductive material). In some cases, the antenna assembly  508  may be formed using insert molding techniques. For example, the antennas may be formed and then inserted into a mold, after which the polymer for the antenna frame  802  may be injected into the mold to at least partially encapsulate and interlock with (or otherwise retain) the antennas to the antenna frame  802 . As another example, the antennas may be conductive tapes or films that are adhered or otherwise attached to the antenna frame  802 . As another example, the antennas may be formed using laser direct structuring (LDS). In one example LDS process, the polymer material of the antenna frame  802  may be doped with a metallic material (or other suitable dopant), and a laser may be applied to the component to form regions where the metallic material or dopant is exposed or otherwise activated. These regions may then be metallized using a plating process in which the plating metal adheres to and/or grows on the laser-treated regions. In this way, the shapes of the antennas can be defined by the laser process, and the resulting antennas may be easily plated on the antenna frame  802  in the target shape and configuration. In other cases, the antennas may be formed and/or integrated with the antenna frame  802  in other ways. For example, antennas may be plated on the antenna frame  802 , attached to the antenna frame  802  using an adhesive, fastener, or any other suitable attachment technique. Further, the laser process may remove some of the material of the antenna frame  802 , thus forming recesses (which may be microscopic in size) in which the antenna material is deposited or grown. Depositing or growing the material of the antennas in the recesses may result in the antennas being at least partially embedded in the material of the antenna frame  802 . 
     The antenna assembly  508  may include any number of antennas. As shown, the antenna assembly  508  includes a near-field wireless communications antenna  804 , a UWB antenna  806 , and a Bluetooth antenna  808 . Each antenna may be tuned to communicate at certain frequencies and/or otherwise comply with applicable communications protocols and/or standards. More generally, an antenna assembly may include multiple antennas, with each antenna configured to communicate via a different wireless communications protocol. For example, a first antenna may communicate (including by transmitting a wireless signal) via a first wireless protocol, a second antenna may communicate (including by transmitting a wireless signal) via a second wireless protocol, and a third antenna may communicate (including by transmitting a wireless signal) via a third wireless protocol. More or fewer antennas may also be embedded in or otherwise attached to an antenna frame. 
     The near-field wireless communications antenna  804  may be configured for any suitable type or protocol of near-field wireless communications, including but not limited to near-field communications (NFC) protocols, radio frequency identification (RFID) protocols, or any other suitable type or protocol. The near-field wireless communications antenna  804  may be a loop antenna, and may include a flat coil of conductive material. The coil may include four turns of coil, or any other suitable number of turns. 
     In some cases, the near-field wireless communications antenna  804  is configured to cause nearby devices to display information. For example, a person may bring a phone, watch, tablet computer, or other device nearby the tag  500  (either intentionally or unintentionally), thereby establishing a communication link between the tag  500  and the person&#39;s device. The communication link may cause the person&#39;s device to display various types of information or take other actions. For example, the person&#39;s device may receive information, via the near-field wireless communications antenna  804 , stating whether or not the tag  500  has been reported lost, information about how to handle the tag  500  (or object to which the tag is attached), information about how to contact the owner of the tag  500 , or the like. The near-field wireless communications antenna  804  may also be used to initiate an initialization process between the tag  500  and another device. Other information may be communicated, or actions triggered, via the near-field wireless communications antenna  804 . 
     The UWB antenna  806  may be configured to communicate using an ultra-wideband protocol, and may be part of a UWB radio system of the tag  500 . The UWB antenna  806  may be configured to communicate in a frequency range from about 6.25 GHz to about 8.25 GHz. The UWB antenna  806  may be configured as an inverted-F antenna. The tag  500  may include a feed line  812  and a ground line  810  electrically coupled to the UWB antenna  806  to allow radio circuitry associated with the UWB antenna  806  to send and receive electromagnetic signals via the UWB antenna  806 . The ground line  810  may be conductively coupled to an electrical ground plane of the tag. 
     The dimensions of the UWB antenna  806  and the locations of the feed and ground lines  812 ,  810  may determine the tuning of the antenna, such as the frequency range over which the antenna may communicate, as well as the bandwidth of the antenna. The feed and ground lines  812 ,  810  may be attached to vias that extend through the antenna frame  802  of the antenna assembly  508  and are conductively coupled to the circuit board  510  to conductively couple the UWB antenna  806  to radio circuitry on the circuit board  510 . 
     In some cases, a greater the height of the UWB antenna  806  corresponds to a greater bandwidth. Accordingly, the UWB antenna  806  may have a height that is 90% or greater of the height of a peripheral side surface of the antenna assembly  508 . The height may be 95% or greater, 98% or greater, or 100% of the height of the peripheral side surface of the antenna assembly  508 . Other heights are also contemplated. 
     The Bluetooth antenna  808  may be configured to facilitate communications using a Bluetooth protocol, such as Bluetooth Low Energy or any other suitable Bluetooth protocol or standard. The Bluetooth antenna  808  may be configured as an inverted-F antenna, and may include feed and ground lines similar to those described with respect to the UWB antenna  806 . (The feed and ground lines of the Bluetooth antenna  808  may be connected to the circuit board  510  using vias similar to those described with respect to the UWB antenna  806 . The Bluetooth antenna  808  and the UWB antenna  806  may be used for different functions. For example, the Bluetooth antenna  808  may be used primarily for communicating information between a tag and another device (e.g., a smartphone), while the UWB antenna  806  may be used primarily for sending localization signals to another device. Localization signals may be used to determine spatial parameters of a tag. Of course, the antennas  806 ,  808  may be used for different functions or combinations of functions. For example, the UWB antenna  806  may be used to communicate data or other information or signals to other devices instead of or in addition to the Bluetooth antenna  808 . 
     The UWB antenna  806  and the Bluetooth antenna  808  may be positioned on an outer peripheral side surface of the antenna assembly  508 . This positioning of the antennas helps maximize the distance between the radiating structures of the antennas and other conductive components within the tag  500 . For example, capacitive coupling between the antennas and conductive components on the circuit board  510 , the battery  514 , or other metal or conductive objects may negatively impact the operation of the antennas. Accordingly, positioning the antennas on the outer peripheral side surface of the antenna assembly  508  (which may be circular) maximizes the distance between the antennas and other conductive components, thereby providing superior antenna performance. Positioning the antennas on the outer peripheral side surface may also position the antennas past the outer perimeter of the battery  514 , thereby mitigating shielding and/or blocking effects of the battery  514 . 
     Further, the UWB antenna  806  and the Bluetooth antenna  808  may be positioned on opposite sides of the antenna frame  802  (e.g., antipodally positioned about the substantially circular or cylindrical outer peripheral side). This configuration provides the maximum possible distance between the antennas with them both being on the same carrier. This arrangement may help mitigate interference or other deleterious effects that may occur if the antennas are close together. 
     Further, the UWB antenna  806  and the Bluetooth antenna  808  may have different lengths. For example, each antenna may be configured to communicate via a different frequency or set of frequencies, and the length of the antennas may at least partially define the frequencies with which the antennas communicate. Accordingly, the UWB antenna  806  may have a different length (e.g., longer or shorter than) the Bluetooth antenna  808 . 
     The UWB antenna  806  and the Bluetooth antenna  808  may be positioned on opposite sides of the antenna frame  802  (e.g., antipodally positioned about the substantially circular or cylindrical outer peripheral side). This configuration provides the maximum possible distance between the antennas with them both being on the same carrier. This arrangement may help mitigate interference or other deleterious effects that may occur if the antennas are close together. 
     The antennas  804 ,  806 ,  808  may each be conductively coupled to circuitry on the circuit board  510  to facilitate communications via the antennas  804 ,  806 ,  808 . As used herein, an antenna and the communication circuitry associated with that antenna may be referred to as a radio. 
       FIG.  8 B  depicts another example antenna assembly  820  that may be used as an alternative to the antenna assembly  508  described above. The antenna assembly  820  may be the same as or similar to the antenna assembly  508  except that the UWB antenna and the Bluetooth antennas may have a different configuration. Accordingly, the antenna assembly  820  may include an antenna frame  822  and a near-field wireless communication antenna  824 , which may be the same as or similar to the corresponding components of the antenna assembly  508 . 
     Whereas the UWB antenna  806  included a single radiating element, the UWB antenna  826  may include a first antenna element  828  and a second antenna element  830  that is set apart from the first antenna element  828 . A feed line  834  and a ground line  832  may be conductively coupled to the first antenna element  828 , and the ground line  832  may be conductively coupled to the second antenna element  830  (via a conductor that is at least partially embedded in the antenna frame  822 , as shown, or via another conductor). The second antenna element  830  may not be directly conductively coupled to the feed line  834 . The second antenna element  830  may act as a parasitic element that can amplify or enhance the effectiveness of the first antenna element  828 , and may provide greater bandwidth than a single-antenna-element configuration. 
     The Bluetooth antenna  833  may include the two-element configuration of the UWB antenna  826 , or it may have the same single-radiator configuration of the Bluetooth antenna  808 . In all other ways, including the composition of the antennas and antenna frame, and the techniques for forming the antennas and integrating them with the antenna frame, the antenna assembly  820  may be the same as or similar to the antenna assembly  508  described above with respect to  FIG.  8 A . 
     While  FIGS.  8 A- 8 B  illustrate two example antenna assemblies, antennas may be integrated with tags in other ways instead of or in addition to those described with respect to  FIGS.  8 A- 8 B .  FIG.  8 C , for example, illustrates an example top housing member  840  (which may be an embodiment of the top housing member  502 ) in which antennas  842 ,  844 , and  846  are attached to the interior walls of the top housing member  840 . The antennas  842   844  may be UWB and Bluetooth antennas, respectively, and may be positioned on the interior surface of the outer peripheral wall of the top housing member  840 . The antenna  846  may be a near-field wireless communication antenna, and may be positioned on the interior surface of the top wall of the top housing member  840 . The antennas may be formed using the same techniques and materials described with respect to the other antenna assemblies described herein (e.g., laser direct sintering, insert molding, adhering conductors to the housing member, etc.). The antennas  842 ,  844 , and  846  may be conductively coupled to circuitry on the circuit board  510  using wires, solder joints, vias, or the like. 
       FIGS.  8 D- 8 E  illustrate another example antenna configuration for a tag  850 . In particular, as shown in  FIG.  8 D , the tag  850  includes a top housing member  852  that includes a central member  854 , which may be formed of a nonconductive material such as a polymer, and conductive elements  856  defining portions of the outer peripheral wall of the tag  850 . The outer peripheral wall of the tag  850  may also be defined at least in part by nonconductive elements  858  that are positioned between the conductive elements  856 . The conductive elements  856  may be set apart from one another by gaps, and the nonconductive elements  858  may be positioned within the gaps. The nonconductive elements  858  may also mechanically secure the conductive elements  856  together by engaging (e.g., interlocking) with the conductive elements  856 . 
       FIG.  8 E  illustrates the inside of the top housing member  852 , showing how both the conductive elements  856  and the nonconductive elements  858  may define part of the internal surfaces of the top housing member  852 . As shown, the width of the nonconductive elements  858  may be greater on the inside of the top housing member  852  than on the outside. The increased internal size may result from the nonconductive elements  858  engaging with retention features, undercuts, openings, grooves, threads, or other features of the conductive elements  856 . The conductive elements  856  may be used as antenna elements for the tag  850 . The electrical isolation provided by the nonconductive elements  858  between the conductive elements  856  may facilitate tuning of the size and radiating characteristics of the conductive elements  856 . The conductive elements  856  may be conductively coupled to circuitry on the circuit board  510  using wires, solder joints, vias, or the like, to allow the conductive elements  856  to operate as antennas. 
     As described above, antennas of an antenna assembly may be conductively (and mechanically) coupled to a circuit board or other electronic component using vias. For example, the ground line  810  and feed line  812  shown in  FIG.  8 A  may be formed in part by vias that extend through the antenna frame and are conductively coupled to a circuit board. The vias in the antenna frames may allow the antenna frame to be surface mounted to the circuit board. More particularly, the vias of the antenna frame may be soldered directly to the circuit board, thus providing both a conductive coupling between circuit elements on the circuit board (e.g., radio circuitry) and components on the antenna frame (e.g., antennas), and also providing a mechanical attachment between the antenna frame and circuit board. 
       FIG.  8 F  illustrates a partial cross-sectional view of the antenna assembly  508  of  FIG.  8 A , viewed along line  8 F- 8 F in  FIG.  8 A .  FIG.  8 F  illustrates an example configuration of a via for conductively and mechanically coupling the circuit board  510  to the antenna assembly  508 . 
     The antenna frame  822  defines an opening  861  that extends from a top surface of the antenna frame  822  to a bottom surface of the antenna frame  822 . The opening  861  may be tapered from a larger opening size (e.g., diameter) at the top surface  865  to a smaller opening size (e.g., diameter) at the bottom surface  863  of the antenna frame  822 . In some cases, the opening  861  may be a frustoconical opening (e.g., an opening defined by a frustoconical wall), with the smaller end of the frustoconical opening along the bottom surface  863  of the antenna frame  822 . 
     A surface  867  of the frustoconical opening (e.g., the surface of a frustoconical wall) is coated with a conductive material  862 . The conductive material  862  may be or may include a metal or other conductive material, and may be formed using an LDS process, as described above. In some cases, the conductive materials of the vias, the antennas, and the conductive traces that join the antennas to the conductive materials of the vias (e.g., conductive trace  860 ) are all formed using the same LDS operations. For example, the surfaces of the antenna frame  822  that are to be metallized (e.g., the antenna  806 , the trace  860 , the surface  862  of the opening  861 ) may be treated with a laser to expose a dopant in the antenna frame  822  and/or to form a distinct surface texture on the antenna frame  822  at the locations where metallization is to occur. The antenna frame  822  is then plated (e.g., electroplated) or otherwise processed so that the laser-treated areas of the antenna frame  822  are coated with a conductive material (e.g., a metal layer). In this way, a continuous metal layer may define the antenna  806 , trace  860 , and the conductive coating or material on the surface of the opening  861 . 
     To conductively couple the antenna to the circuit board, the via may be soldered to a conductive trace  866  of the circuit board  510 . This may be achieved by soldering a solder ball  864  in the frustoconical opening  861  of the via, which defines a reliable conductive path from the conductive material  862  to the conductive trace  866 . 
     Additionally, the tapered configuration of the opening  861 , as well as the mechanical bond between the solder ball  864  and the conductive trace  866  and the solder ball  864  and the conductive material  862 , results in the solder ball  864  mechanically interlocking the circuit board  510  with the antenna frame  822 . For example, the process of soldering the solder ball  864  to the conductive trace  866  and to the conductive material  862  forms a bond (e.g., a metal fusion bond) between those materials, and the resulting tapered shape of the solder ball  864  essentially defines an undercut that captures or traps the narrower end of the opening  861  between the solder ball  864  and the surface of the circuit board  510 . This interlocking structure, along with the metal-to-metal bonds, forms a structural attachment between the antenna frame  822  and circuit board. Further, the tapered configuration of the opening  861  results in an advantageous stress profile on the conductive material  862 . For example, if a tag experiences a force that stresses the antenna frame-circuit board interface, the forces that are imparted to the conductive material  862  may be primarily compression and/or shear forces, rather than tensile forces (where tensile forces correspond to forces that lift the conductive material away from the antenna frame  822 ). Thus, a force that tends to pull the circuit board  510  away from the antenna frame  822  (e.g., downwards) results in the conductive material  862  being compressed between the solder ball  864  and the underlying surface of the antenna frame  822  (which tends to force the conductive material  862  against the underlying surface of the antenna frame  822 , rather than pulling it away from the antenna frame  822 ). 
       FIG.  9    depicts a partial exploded view of a portion of an example wirelessly locatable tag  500 , showing how a battery connector  900  may conductively couple the battery  514  to the circuitry of the device (e.g., via the circuit board  510 ). The battery connector  900  may include multiple deflectable arms (three, as shown), portions of which extend through openings  902 ,  904 , and  906  in the frame member  512  to contact the positive and negative terminals of the battery  514 . The deflectable arms may define battery contacts of the tag (e.g., conductive members that conductively couple to positive and/or negative terminals of a battery). The battery connector  900  may be mounted on and conductively coupled to the circuit board  510  to provide power from the battery  514  to the electronics of the tag  500 . 
     In some cases, at least a portion of each of two of the three deflectable arms may extend through the openings  902 ,  904  to contact one of the terminals of the battery (e.g., the positive terminal  910 , which may be or may be defined at least in part by a curved or cylindrical surface of the battery), and the third deflectable arm extends through the opening  906  to contact the other terminal of the battery (e.g., the negative terminal  908 , which may be or may be defined at least in part by a planar surface of the battery). By contacting one of the battery terminals with two deflectable arms, the tag  500  is able to detect whether the battery is present in the battery cavity by detecting whether there is continuity between those two deflectable arms. When the battery is not present, the device may be shut down, and any residual voltage stored in capacitors or other circuit elements may be discharged so that the tag  500  ceases to function as soon as the battery is no longer detected in the tag  500 . The openings  902 ,  904 , and  906  may also fluidly couple the battery cavity to the other portions of the internal volume of the tag  500 , such as the portions that are above the frame member  512  (based on the orientation shown in  FIG.  9   ). 
       FIG.  10 A  illustrates the opposite side of the circuit board  510  (compared to  FIG.  9   ), showing the battery connector  900  attached to the circuit board  510 . Also shown are electrical components  1000 , which represent processors, memory, sensors, and/or other electrical components and/or circuit elements that may be coupled to the circuit board  510 . 
       FIG.  10 B  is a detail view of the area  10 B- 10 B in  FIG.  10 A , showing additional details of the battery connector  900  and its components. The battery connector  900  includes a body  1002 , first and second deflectable arms  1004 ,  1006  extending from the body  1002  and configured to contact the positive terminal of the battery  514 , and a third deflectable arm  1008  configured to contact the negative terminal of the battery  514 . The deflectable arms may be electrically coupled to the circuit board  510  via conductors that are embedded in the body  1002  and soldered or otherwise conductively coupled to the circuit board  510 . 
     The deflectable arms may be biased in a direction that forces them into contact with the battery  514  when the battery  514  is within the battery cavity of the tag  500 . This biasing may help ensure that the deflectable arms are forced into contact with the battery  514  to maintain a positive conductive contact with the battery  514 . The direction that the deflectable arms move and/or are biased is based at least partly on the orientation of the deflectable arms relative to the battery. For example, as is evident from the location of opening  906  ( FIG.  9   ), the third deflectable arm  1008  contacts the battery  514  from above the battery  514  (relative to the orientation shown in  FIG.  9   ). Accordingly, the third deflectable arm  1008  is configured to deflect along a direction indicated by arrow  1016  in  FIG.  10 B  (e.g., towards and away from the circuit board  510 ). A cut-out  1001  in the circuit board  510  provides clearance so that the third deflectable arm  1008  can deflect without interference by the circuit board  510 . By contrast, the first and second deflectable arms  1004 ,  1006  contact the battery  514  along the side of the battery  514 , or at least along a surface that is not parallel to the circuit board  510 . Accordingly, the first and second deflectable arms  1004 ,  1006  are configured to deflect along directions indicated by the arrows  1014 . 
     As the battery  514  is being inserted into the battery cavity of the tag  500 , however, the battery  514  may apply a force to the first and second deflectable arms  1004 ,  1006  tending to push the first and second deflectable arms  1004 ,  1006  towards the circuit board  510 . The circuit board  510  may include friction pads  1010  and  1012  that are positioned below portions of the first and second deflectable arms  1004 ,  1006 , respectively. The friction pads  1010 ,  1012  may be formed of metal (e.g., copper, gold), or any other suitable material that allows the first and second deflectable arms  1004 ,  1006  to slide along the circuit board  510  while providing a relatively low coefficient of friction between the circuit board  510  and the first and second deflectable arms  1004 ,  1006 . The friction pads  1010 ,  1012  may also protect the circuit board&#39;s substrate and the first and second deflectable arms  1004 ,  1006  from wear due to sliding of the first and second deflectable arms  1004 ,  1006  along the surface. During installation of the battery  514 , the battery may contact the first and second deflectable arms  1004 ,  1006  in a manner that pushes them towards the circuit board  510 . By providing the friction pads  1010 ,  1012  on the circuit board  510  and configuring the first and second deflectable arms  1004 ,  1006  so that they are proximate the friction pads  1010 ,  1012  (and also configuring the ends of the first and second deflectable arms  1004 ,  1006  to have a rounded shape), the deflection of the first and second deflectable arms  1004 ,  1006  in the direction towards the circuit board  510  is limited by the contact between the arms and the friction pads. Limiting deflection in this direction allows the first and second deflectable arms  1004 ,  1006  to begin deflecting along the directions  1014 ,  1016 , thereby allowing the first and second deflectable arms  1004 ,  1006  to move out of the way of the battery  514  and provide the biasing force in the appropriate direction to maintain the first and second deflectable arms  1004 ,  1006  in contact with the battery  514 . 
       FIG.  10 C  shows a bottom side view of the battery connector  900 . The battery connector  900  includes solder pads that are soldered to the circuit board  510  to conductively couple the deflectable arms  1004 ,  1006 ,  1008  to conductive traces on the circuit board. More specifically, the battery connector  900  includes a first solder pad  1018  that is conductively coupled to the first deflectable arm  1004 , a second solder pad  1020  that is conductively coupled to the second deflectable arm  1006 , and a third solder pad  1022  that is conductively coupled to the third deflectable arm  1008 . In some cases, the solder pads and their respective deflectable arms are unitary metal structures (e.g., the solder pad and the deflectable arm are a single piece of metal, such as stamped metal). In other cases, the solder pads and their respective deflectable arms are separate components that are attached via welding, soldering, or another operation. 
     The battery connector  900  may be formed by insert molding. For example, the deflectable arms  1004 ,  1006 ,  1008  and the solder pads  1018 ,  1020 ,  1022  (or the unitary metal structures that define the deflectable arms and the solder pads) may be inserted into a mold, and an insulating, polymer material may be introduced into the mold, thereby at least partially encapsulating the deflectable arms  1004 ,  1006 ,  1008  and the solder pads  1018 ,  1020 ,  1022 . Other techniques for forming the battery connector  900  are also contemplated. 
       FIG.  10 D  illustrates a partial cross-sectional view of another example configuration for a battery connector. In particular, whereas the deflectable arms of the battery connector  900  extend into the battery cavity through openings in the main frame member  512  (so that the deflectable arms can conductively couple to the battery  514  by directly contacting the battery  514 ), in another configuration conductive plugs may be positioned in the openings in the main frame member, and the deflectable arms may conductively contact the conductive plugs to ultimately conductively couple the deflectable arms to the battery.  FIG.  10 D  illustrates such a configuration. In particular, the tag includes a conductive plug  1026  positioned in the opening  906  in the main frame member  512  and extending into the battery cavity defined by the main frame member  512 . The conductive plug  1026  may be formed of metal, and may be configured to physically contact and conductively couple to the battery  514 . The conductive plug  1026  may be biased into the battery cavity by a deflectable arm  1024  (which may be similar to the third deflectable arm  1008  except that it does not extend into the battery cavity). The biasing force applied by the deflectable arm  1024  may be opposed by the force applied on the conductive plug  1026  by the battery  514 , thereby causing the conductive plug  1026  to move upwards (relative to the orientation in  FIG.  10 D ). The biasing force applied by the deflectable arm  1024  also maintains an intimate physical connection between the battery  514  and the conductive plug  1026 . Further, the biasing force applied by the deflectable arm  1024  retains the conductive plug  1026  in place by capturing the conductive plug  1026  between the deflectable arm  1024  and the main frame member  512 . 
     The conductive plug  1026  may be configured to self-align in the opening  906 . For example, the conductive plug  1026  may have a rounded protrusion, and the opening  906  may be a circular hole, such that the rounded protrusion self-aligns in a substantially concentric position (with respect to the circular hole). This self-aligning property of the conductive plug  1026  may also help accommodate for misalignments between the deflectable arms  1004 ,  1006 ,  1008  and the openings  902 ,  904 ,  906  in the main frame member  512 . For example, misalignments between the deflectable arms and the openings can be tolerated because the deflectable arms merely need to contact the conductive plugs to provide a biasing force and conductive connection. More particularly, because the conductive plugs are not fixed to the deflectable arms, as long as a deflectable arm conductively couples to and provides sufficient biasing and/or retention force on the conductive plug, the contact point between the deflectable arm and the conductive plug can vary. Accordingly, because the conductive plugs can self-align in the openings and misalignments between the deflectable arms and the conductive plugs are accommodated by the non-fixed arm/plug interface, assembly tolerances relating to the positioning of the battery connector and the position of the circuit board and main frame member may be relaxed. 
     While  FIG.  10 D  illustrates one deflectable arm and conductive plug, the same or a similar configuration may be used for any and all battery contacts. For example, conductive plugs may be positioned in the openings  902 ,  904 , and deflectable arms similar to the first and second deflectable arms  1004 ,  1006  may contact and bias those conductive plugs into the battery cavity. Indeed, any of the battery contacts shown or described herein may be portions of deflectable arms that extend into the battery cavity, or they may be conductive plugs that extend into the battery cavity, with deflectable arms biasing and retaining the conductive plugs as described above. 
     While  FIGS.  9 - 10 C  depict one example battery connector and arrangement of deflectable arms (including where the deflectable arms contact the battery  514 ), this is merely one example configuration, and other configurations may also be used with the tag  500 , or any other tag shown and described herein.  FIGS.  11 A- 11 D  illustrate alternative arrangements of deflectable arms or other types of battery contacts that may be used to provide an electrical connection to the battery  514 . Each of these alternative arrangements may use a battery connector that is similar to the battery connector  900 . In some cases, each battery contact shown in  FIGS.  11 A- 11 D  corresponds to an end of a deflectable arm similar to those of the battery connector  900 . In some cases, instead of having all of the deflectable arms coupled to the same body (as is the case with the battery connector  900 ), one or more of the deflectable arms that define the battery contacts in  FIGS.  11 A- 11 D  are coupled to separate bodies. While  FIGS.  11 A- 11 D  discuss the position of battery contacts, it will be understood that the battery contacts may be the ends of deflectable arms similar to those described with respect to the battery connector  900 . Further, battery contact configurations other than those shown in  FIGS.  9 - 11 D  may also be used to conductively couple a battery to the circuitry of a tag. 
       FIG.  11 A  shows an example tag  1100  in which first and second battery contacts  1102 ,  1104  are positioned along a side wall of a battery cavity  1101 , and a third battery contact  1106  is positioned at a center of the battery cavity  1101 . The first and second battery contacts  1102 ,  1104  are configured to contact the positive terminal of the battery, and the third battery contact  1106  is configured to contact the negative terminal of the battery. 
       FIG.  11 B  shows an example tag  1110  in which two battery contacts are configured to contact the negative terminal of the battery, and one is configured to contact the positive terminal of the battery (in contrast to the battery connector  900  and the configuration in  FIG.  11 A , in which two battery contacts contact the positive terminal and one battery contact contacts the negative terminal). In particular, first and second battery contacts  1112 ,  1114  are positioned on a bottom surface of a battery cavity  1111  (relative to the orientation shown in  FIG.  11 B ), and a third battery contact  1116  is positioned along a side wall of the battery cavity  1111 . The first and second battery contacts  1112 ,  1114  have elongated arcuate shapes, which may be symmetrical about a center of the circular battery cavity  1111 . The first and second battery contacts  1112 ,  1114  are configured to contact the negative terminal of the battery, and the third battery contact  1116  is configured to contact the positive terminal of the battery. Also, the tag  1110  may be configured to detect the presence of the battery by detecting continuity between the first and second battery contacts  1112 ,  1114 . For example, if there is continuity between the first and second battery contacts  1112 ,  1114 , that may indicate that a battery is present in the battery cavity  1111  (regardless of whether the charge state of the battery). 
       FIG.  11 C  shows another example tag  1120  in which two battery contacts are configured to contact the negative terminal of the battery, and one is configured to contact the positive terminal of the battery. In particular, first and second battery contacts  1122 ,  1124  are positioned on a bottom surface of a battery cavity  1121  (relative to the orientation shown in  FIG.  11 C ), and a third battery contact  1126  is positioned along a side wall of the battery cavity  1121 . The first and second battery contacts  1122 ,  1124  have rounded (e.g., circular) shapes, in contrast to the arcuate shapes of the contacts in  FIG.  11 B . The first and second battery contacts  1122 ,  1124  are configured to contact the negative terminal of the battery, and the third battery contact  1126  is configured to contact the positive terminal of the battery. Also, the tag  1120  may be configured to detect the presence of the battery by detecting continuity between the first and second battery contacts  1122 ,  1124 . 
       FIG.  11 D  shows another example tag  1130  in which two battery contacts are configured to contact the negative terminal of the battery, and one is configured to contact the positive terminal of the battery. In particular, first and second battery contacts  1132 ,  1134  are positioned on a bottom surface of a battery cavity  1131  (relative to the orientation shown in  FIG.  11 D ), and a third battery contact  1136  is positioned along a side wall of the battery cavity  1131 . The first and second battery contacts  1132 ,  1134  have elongated arcuate shapes, which may be symmetrical about a center of the circular battery cavity  1131 . In this example, the third battery contact  1136  also has an elongated arcuate shape that conforms to the circular shape of the side wall of the battery cavity  1131 . 
     In some cases, the battery door of a tag may also act as one of the battery contacts. For example, the battery door (e.g., the bottom housing member  516 ) may be formed of or include metal or another conductive material, and at least one terminal of the battery may be conductively coupled to the battery door. The battery door may, in turn, be conductively coupled to the circuit board. In this manner, at least one terminal of the battery (e.g., the positive terminal) may be conductively coupled to the circuit board via a conductive path that includes the battery door. 
       FIG.  12 A  is a partial exploded view of the tag  500 , illustrating features of the bottom housing member  516  (or battery door  516 ) and how the battery door  516  engages the rest of the tag  500  and how the battery  514  is retained in the tag  500  and biased towards the battery contacts of the tag  500 . 
     The bottom housing member  516  may include latching members  1200  and the frame member  512  may define latching channels  1202  that are configured to engage the latching members  1200  to secure the bottom housing member  516  to the tag  500 . The latching members  1200  and channels  1202  may be configured so that in order to remove the bottom housing member  516 , the user must manipulate the bottom housing member  516  in multiple different directions (e.g., by both pressing on and turning the bottom housing member  516 ). This may help prevent unintended opening of the battery cavity, and may help prevent children from removing the button cell battery (which may pose choking or other hazards if removed from the tag  500 ). 
       FIG.  12 B  illustrates a detail view of how a latching member  1200  engages a latching channel  1202  when the bottom housing member  516  is being attached to the tag  500 . In particular, the bottom housing member  516  is aligned with the tag  500  (e.g., with the frame member  512  of the tag) such that the latching members  1200  are aligned with openings  1203  of the latching channels  1202 . (For simplicity, the following description refers only to a single latching member and channel, but the tag  500  may include any suitable number of latching member/channel pairs, such as two, three, four, five, or more pairs.) The bottom housing member  516  is then pushed downwards, following the path  1208 , until the latching member  1200  passes a retention protrusion  1204 . The operation of pushing the latching member  1200  past the retention protrusion  1204  may include overcoming a spring force, provided by the compliant member  518 , that tends to bias the bottom housing member  516  in an upwards direction, relative to the orientation shown in  FIG.  12 B . 
     After passing the retention protrusion  1204 , and while maintaining a downward force on the bottom housing member  516  to overcome the biasing force, the user may twist or rotate the bottom housing member  516  to cause the latching member  1200  to continue along the path  1208  and move towards a recess  1206 . Once the latching member  1200  is aligned with the recess  1206 , such as because the latching member  1200  reaches the end of the latching channel  1202 , the user may release the downward force on the bottom housing member  516 , thereby causing the compliant member  518  to bias the bottom housing member  516  upwards and forcing the latching member  1200  into the recess  1206 . Because the retention protrusion  1204  and the blind end of the latching channel  1202  block movement of the latching member  1200  in the horizontal direction (corresponding to a rotation or twisting of the bottom housing member  516 ), combined with the biasing force from the compliant member  518  tending to force the latching member  1200  into the recess  1206  (or with another surface of the latching channel  1202 ), the bottom housing member  516  may be securely retained to the tag  500  and may resist inadvertent or accidental opening. 
     In order to detach the bottom housing member  516  from the tag, the operation described with respect to  FIG.  12 B  may be reversed, as shown indicated by the path  1210  in  FIG.  12 C . Initially, a user applies a downward force to the bottom housing member  516  to move the latching member  1200  out of the recess  1206  and below the retention protrusion  1204 . Once the latching member  1200  is clear of the retention protrusion  1204 , and while maintaining the downward force on the bottom housing member  516 , the bottom housing member  516  is rotated or twisted to move the latching member  1200  horizontally until it is aligned with the opening  1203  of the latching channel  1202 , at which time the bottom housing member  516  may be forced upwards by the biasing force of the compliant member  518  and/or by the user pulling the bottom housing member  516  away from the tag  500 . 
     The tag  500  may also include detents or other mechanisms to provide haptic or tactile sensations to a user during attachment and/or detachment of the bottom housing member  516 . For example, the tag  500  may include a ball detent that engages a recess in the bottom housing member  516  when the bottom housing member  516  is rotated or twisted during attachment and/or detachment. As the ball detent engages the recess, the user may feel a clicking or other tactile sensation, indicating that the bottom housing member  516  is moving or has reached a particular position (e.g., a fully closed position). The detent (or other mechanism) may be attached to the bottom housing member  516  to engage a recess in the main frame member  512 , or it may be attached to the main frame member  512  to engage a recess in the bottom housing member  516 . Other configurations are also possible. Further, detents or other mechanisms may be provided for any moving or detachable components of tags described herein, and may be provided solely for the tactile indication that they provide during manipulation of the components, or for other additional functions (e.g., to removably retain a battery door, housing member, or other component in a particular position). 
     The compliant member  518  may provide a biasing force that both helps bias the bottom housing member  516  into an engaged or locked configuration (as described with respect to  FIGS.  12 A- 12 C ), and bias the battery  514  towards the battery contacts of the battery connector  900 .  FIG.  13 A  illustrates the compliant member  518 . The compliant member  518  defines a base  1301  that may be attached to an inner surface of the bottom housing member  516  (e.g., via adhesive, welding, soldering, fasteners, or any other suitable attachment technique). The compliant member  518  may also define spring arms  1300  that extend from the base  1301  and are configured to contact the battery  514 . The base  1301  and spring arms  1300  may be defined by a single unitary piece of material. The material may be any suitable material, including but not limited to metal (e.g., stainless steel), a polymer, or the like. 
     As described above, the compliant member  518  also defines a flange portion  714 , which may also be defined by the same single piece of material that defines the base  1301  and spring arms  1300 . The flange portion  714  may be configured to help retain a membrane and/or other components near an opening that allows pressure equalization. The flange portion  714  may also define an opening  710  that aligns with the pressure equalization opening. 
       FIG.  13 B  is a partial cross-sectional view of the tag  500 , illustrating the operation of the compliant member  518 . As shown, the bottom housing member  516  is attached to the frame member  512 , a state that results in the compliant member  518  being compressed or otherwise in a state that produces a biasing force. More particularly, the spring arms  1300  are pressed against the battery  514 , causing the compliant member  518  to produce a force (indicated by arrow  1302 ) tending to push the battery  514  towards the frame member  512  and push the bottom housing member  516  away from the frame member  512 . This ultimately forces the battery  514  into contact with the deflectable arms of the battery connector  900  and helps maintain the secure engagement of the latching members  1200  with the latching channels  1202  ( FIGS.  12 A- 12 C ). 
     The presence of the compliant member  518  may also facilitate the use of battery connectors that do not deflect. For example, any of the battery contacts and/or deflectable arms described above for conductively coupling to a battery may be configured to not deflect when a battery is inserted into the battery cavity. In such cases, the compliance of the compliant member  518  both biases the battery  514  against the non-deflecting battery contacts to ensure conductive coupling, and also provides clearance to the battery to accommodate for any canting or misalignment of the battery due to the non-deflecting battery contacts. 
     While  FIG.  13 A  shows one example configuration of a compliant member for biasing the bottom housing member  516  and the battery  514 , other types of compliant members may also be used.  FIG.  13 C  illustrates one such alternative example compliant member  1310 . The compliant member  1310 , which may be formed from a single piece of metal, polymer, or the like, defines a base  1312  and three curved spring arms  1314 , each extending along a circular path inside the perimeter of the base  1312  and extending from the base  1312 . Other configurations of unitary metal compliant members are also contemplated. Further, other components, mechanisms, or systems may be used instead of or in addition to unitary metal compliant members, including but not limited to coil springs, elastomers, foams, leaf springs, or the like. 
     As noted above, button cell or other small form-factor batteries may be potentially hazardous to people or pets due to their small size and possibility of being ingested. To avoid the batteries from accidentally falling out of the tags, the tags may be configured so that their battery doors require more than a simple, single motion (e.g., twisting) to remove them.  FIGS.  12 A- 12 C , for example, illustrate one configuration that requires a user to both press and twist the battery door (e.g., the bottom housing member  516 ) in order to open it. Other mechanisms may also be used to securely retain a battery door to a tag in a manner that prevents or limits accidental opening and satisfies applicable laws or regulations for device safety.  FIGS.  14 A- 25 C  illustrate several example configurations of such retention mechanisms. 
       FIGS.  14 A- 16 D  illustrate various aspects of an example mechanism for securely retaining a battery door (e.g., a bottom housing member) to a tag.  FIG.  14 A  illustrates a portion of a frame member  1400  that defines a channel  1402  and a spring member  1404  that extends into the channel  1402  and/or defines part of the channel. The frame member  1400  may be an embodiment of the frame member  512 , and may include any or all of the components and may provide any or all of the functionality of the frame member  512  (and may be integrated with the tag  500  or any other tag described herein). For brevity such details may not be repeated here. 
       FIG.  14 B  illustrates a portion of a bottom housing member  1406  that is configured to mate with the frame member  1400  in  FIG.  14 A . The bottom housing member  1406  may be an embodiment of the bottom housing member  516 , and may include any or all of the components and may provide any or all of the functionality of the bottom housing member  516 . For brevity such details may not be repeated here. The bottom housing member  1406  includes a pin  1408  that is configured to engage with the frame member  1400  via the channel  1402  and/or the spring member  1404  to retain the bottom housing member  1406  to the frame member  1400 . 
       FIGS.  15 A- 15 B  illustrate a schematic view of the frame member  1400  and the bottom housing member  1406 , showing how the pin  1408  engages the channel  1402  and the spring member  1404  when the bottom housing member  1406  is being attached to the frame member  1400 . As shown in  FIG.  15 A , the bottom housing member  1406  is positioned relative to the frame member  1400  such that the pin  1408  enters the channel  1402 , along the path  1502 . More particularly, the bottom housing member  1406  may be moved vertically (relative to the orientation in  FIG.  15 A ) to position the pin  1408  in the channel  1402 . This manipulation may require overcoming a biasing force (acting in an upward direction) imparted to the bottom housing member  1406  by a spring or other mechanism (such as the compliant member  518 ,  FIG.  5 B ). 
     After positioning the pin  1408  in the channel  1402  as shown in  FIG.  15 A , rotating or twisting the bottom housing member  1406  causes the pin  1408  to move through the channel  1402  along the path  1506  to a blind end  1504  ( FIG.  15 A ) of the channel  1402 . This manipulation results in the pin  1408  contacting a retention feature  1508  of the spring member  1404 , resulting in the spring member  1404  deflecting downwards to accommodate the pin  1408 . The retention feature  1508  may also contact the pin  1408  to retain the pin  1408  in the blind end  1504  of the channel  1402 . The action of sliding the pin  1408  over the retention feature  1508  may also produce a tactile click-like feeling that is detectable by the user when twisting the bottom housing member  1406  into the closed configuration. This tactile sensation may indicate to the user that the bottom housing member  1406  has reached a fully closed and secured position, and that the user can cease turning the bottom housing member  1406 . 
       FIGS.  16 A- 16 D  illustrate a schematic view of the frame member  1400  and the bottom housing member  1406 , showing how the pin  1408  disengages from the channel  1402  and the spring member  1404  when the bottom housing member  1406  is being detached from the frame member  1400 . As shown in  FIG.  16 A , the bottom housing member  1406  is positioned relative to the frame member  1400  such that the pin  1408  is securely maintained in the blind end  1504  of the channel  1402 . In order to detach the bottom housing member  1406 , a user may twist or rotate the bottom housing member  1406 , causing the pin  1408  to slide along the path  1600  in  FIG.  16 B . This motion causes the pin  1408  to contact the retention feature  1508 , which in turn causes the spring member  1404  to deflect downwards. Because the spring member  1404  is biased upwards, the contact between the pin  1408  and the retention feature  1508  produces a resistance to rotation of the bottom housing member  1406  which, when overcome, pushes the spring member  1404  downwards. This interaction between the pin  1408  and the retention feature  1508  provides several benefits, including producing an increased resistance that the user must overcome in order to detach the bottom housing member  1406 , and also potentially producing a tactile click or detent sensation that indicates to the user that the bottom housing member  1406  has been moved out of a securely locked condition. 
     Once the pin  1408  has been moved out of the blind end  1504  of the channel  1402  and as the bottom housing member  1406  continues to be rotated, the biasing force (indicated by arrow  1604 ) between the frame member  1400  and the bottom housing member  1406  forces the bottom housing member  1406  and thus the pin  1408  upwards and into a recess  1602 . The biasing force may be produced by a compliant member between the battery and the bottom housing member  1406 , as described above. The recess  1602  defines a lip that prevents or inhibits further rotation of the bottom housing member  1406 . In order to continue detaching the bottom housing member  1406 , the user must press on the bottom housing member  1406  to provide a downward force  1606  that overcomes the biasing force to push the bottom housing member  1406 , and thus the pin  1408 , downwards and out of the recess  1602  (as indicated by path  1608  in  FIG.  16 C ). 
     Once the pin  1408  is clear of the lip of the recess  1602 , as shown in  FIG.  16 C , the user may continue to rotate the bottom housing member  1406  until the pin  1408  clears the top wall of the channel and is able to be removed from the channel, as indicated by path  1610  in  FIG.  16 D . More specifically, once the pin  1408  is positioned as shown in  FIG.  16 D , the bottom housing member  1406  can be simply lifted away from the frame member  1400  to access the battery. 
       FIGS.  17 A- 19 E  illustrate various aspects of another example mechanism for securely retaining a battery door (e.g., a bottom housing member) to a tag.  FIG.  17 A  illustrates a portion of a frame member  1700  that defines a channel  1702  and a spring member  1704  that extends into the channel  1702  and/or defines part of the channel. The frame member  1700  may be an embodiment of the frame member  512 , and may include any or all of the components and may provide any or all of the functionality of the frame member  512  (and may be integrated with the tag  500  or any other tag described herein). For brevity such details may not be repeated here. 
       FIG.  17 B  illustrates a portion of a bottom housing member  1706  that is configured to mate with the frame member  1700  in  FIG.  17 A . The bottom housing member  1706  may be an embodiment of the bottom housing member  516 , and may include any or all of the components and may provide any or all of the functionality of the bottom housing member  516 . For brevity such details may not be repeated here. The bottom housing member  1706  includes a pin  1708  that is configured to engage with the frame member  1700  via the channel  1702  and/or the spring member  1704  to retain the bottom housing member  1706  to the frame member  1700 . 
       FIG.  17 C  shows the spring member  1704  removed from the frame member  1700 . The spring member  1704  defines two at least partially independently actuatable retention features  1712 ,  1714 . The first retention feature  1712  may be at least partially within an opening in a base  1710 , and the second retention feature  1714  may be formed at an end of the base  1710 . The spring member  1704  may be a unitary component formed of metal, polymer, or any other suitable material. Accordingly, the retention features and the base may be formed from the same piece of material. 
       FIGS.  18 A- 18 B  illustrate a schematic view of the frame member  1700  and the bottom housing member  1706 , showing how the pin  1708  engages the channel  1702  and the spring member  1704  when the bottom housing member  1706  is being attached to the frame member  1700 . As shown in  FIG.  18 A , the bottom housing member  1706  is positioned relative to the frame member  1700  such that the pin  1708  enters the channel  1702 , along the path  1800 . More particularly, the bottom housing member  1706  may be moved vertically (relative to the orientation in  FIG.  18 A ) to position the pin  1708  in the channel  1702 . This manipulation may require overcoming a biasing force (acting in an upward direction) imparted to the bottom housing member  1706  by a spring or other mechanism (such as the compliant member  518 ,  FIG.  5 B ). 
     After positioning the pin  1708  in the channel  1702  as shown in  FIG.  18 A , rotating or twisting the bottom housing member  1706  causes the pin  1708  to move through the channel  1702  along the path  1802  to a blind end  1803  ( FIG.  18 A ) of the channel  1702 . This manipulation results in the pin  1708  contacting both the first and second retention features  1712 ,  1714  of the spring member  1704 , resulting in the both the first and second retention features  1712 ,  1714  deflecting downwards as the pin  1708  contacts them and passes them (as indicated by arrows  1804 ,  1806 ). The second retention feature  1714  may also contact the pin  1708  to retain the pin  1708  in the blind end  1803  of the channel  1702 . The action of sliding the pin  1708  over the retention features  1712 ,  1714  may also produce a tactile click-like feeling that is detectable by the user when twisting the bottom housing member  1706  into the closed configuration. 
       FIGS.  19 A- 19 D  illustrate a schematic view of the frame member  1700  and the bottom housing member  1706 , showing how the pin  1708  disengages from the channel  1702  and the spring member  1704  when the bottom housing member  1706  is being detached from the frame member  1700 . As shown in  FIG.  19 A , the bottom housing member  1706  is positioned relative to the frame member  1700  such that the pin  1708  is securely maintained in the blind end  1803  of the channel  1702 . In order to detach the bottom housing member  1706 , a user may twist or rotate the bottom housing member  1706 , causing the pin  1708  to slide along the path  1900  in  FIG.  19 B . This motion causes the pin  1708  to contact the second retention feature  1714 , which in turn causes the second retention feature  1714  to deflect downwards. Because the second retention feature  1714  is biased upwards, the contact between the pin  1708  and the second retention feature  1714  produces a resistance to rotation of the bottom housing member  1706  which, when overcome, pushes the second retention feature  1714  downwards. This interaction between the pin  1708  and the second retention feature  1714  provides several benefits, including producing an increased resistance that the user must overcome in order to detach the bottom housing member  1706 , and also potentially producing a tactile click or detent sensation that indicates to the user that the bottom housing member  1706  has been moved out of a securely locked condition. 
     Once the pin  1708  has been moved past the second retention feature  1714 , it may come into contact with a surface of the first retention feature  1712  that prevents further rotation of the bottom housing member  1706 , as shown in  FIG.  19 B . Due to the biasing force (indicated by arrow  1906 ) between the frame member  1700  and the bottom housing member  1706 , the bottom housing member  1706  and thus the pin  1708  may be forced upwards along the path  1902  and into a recess  1904 . The biasing force may be produced by a compliant member between the battery and the bottom housing member  1706 , as described above. When the pin  1708  is in the position shown in  FIG.  19 C , the first retention feature  1712  may still be overlapping the pin  1708 , thereby inhibiting further rotational movement. The user may continue to rotate the bottom housing member  1706  to move the pin along the path  1908  ( FIG.  19 D ). This rotation results in the pin  1708  (e.g., a chamfered or angled surface of the pin  1708 ) contacting the first retention feature  1712  and forcing the first retention feature  1712  downward. Like other manipulations resulting in an interaction between a pin and a spring member, this may produce a tactile output that indicates to a user that a particular manipulation has been successfully completed. 
     After the bottom housing member  1706 , and thus the pin  1708 , has been rotated to move the pin  1708  past the second retention feature  1712 , further rotation of the pin  1708  may be inhibited by lip of the recess  1904 . In order to continue detaching the bottom housing member  1706 , the user must press on the bottom housing member  1706  to provide a downward force  1912  that overcomes the biasing force to push the bottom housing member  1706 , and thus the pin  1708 , downwards and out of the recess  1904  (as indicated by path  1910  in  FIG.  19 E ). Once the pin  1708  is clear of the lip of the recess  1904 , as shown in  FIG.  19 D , the user may continue to rotate the bottom housing member  1706  until the pin  1708  clears the top wall of the channel and is able to be removed from the channel, as indicated by path  1910 . 
       FIGS.  20 A- 22 D  illustrate various aspects of another example mechanism for securely retaining a battery door (e.g., a bottom housing member) to a tag.  FIG.  20 A  illustrates a portion of a frame member  2000  that defines a latching region  2002  and a spring member  2004  that extends into the latching region  2002  and/or defines part of the latching region. The frame member  2000  may be an embodiment of the frame member  512 , and may include any or all of the components and may provide any or all of the functionality of the frame member  512  (and may be integrated with the tag  500  or any other tag described herein). For brevity such details may not be repeated here. 
       FIG.  20 B  illustrates a portion of a bottom housing member  2006  that is configured to mate with the frame member  2000  in  FIG.  20 A . The bottom housing member  2006  may be an embodiment of the bottom housing member  516 , and may include any or all of the components and may provide any or all of the functionality of the bottom housing member  516 . For brevity such details may not be repeated here. The bottom housing member  2006  includes a latch  2008  that is configured to engage with the frame member  2000  via the latching region  2002  and/or the spring member  2004  to retain the bottom housing member  2006  to the frame member  2000 . 
       FIG.  20 C  shows the spring member  2004  removed from the frame member  2000 . The spring member  2004  defines a first retention feature  2012  and a second retention feature  2014 . The spring member  2004  may also define a base portion  2010  that is secured to the frame member  2000 . The spring member  2004  may be configured to deflect or move in multiple directions during attachment and detachment of the bottom housing member  2006 . For example, as described herein, an interaction between the latch  2008  and the second retention feature  2014  during attachment of the bottom housing member  2006  may cause the spring member  2004  to deflect along a direction indicated by arrow  2018 , while an interaction between the latch  2008  and the second retention feature  2014  during detachment of the bottom housing member  2006  may cause the spring member  2004  to deflect along a direction indicated by arrow  2016 . The spring member  2004  may be a unitary component formed of metal, polymer, or any other suitable material. 
       FIGS.  21 A- 21 C  illustrate a schematic view of the frame member  2000  and the bottom housing member  2006 , showing how the latch  2008  engages the frame member  2000  and the spring member  2004  when the bottom housing member  2006  is being attached to the frame member  2000 . As shown in  FIG.  21 A , the bottom housing member  2006  is positioned relative to the frame member  2000  such that the latch  2008  enters the latching region  2002 , along the path  2100 . More particularly, the bottom housing member  2006  may be moved vertically (relative to the orientation in  FIG.  21 A ) to position the latch  2008  in the latching region  2002  and into an engagement with the spring member  2004 . This manipulation may require overcoming a biasing force (acting in an upward direction) imparted to the bottom housing member  2006  by a spring or other mechanism (such as the compliant member  518 ,  FIG.  5 B ). 
       FIG.  21 B  illustrates a partial cross-sectional view of the latch  2008  and the spring member  2004 , showing how the latch  2008  and the spring member  2004  interact as the bottom housing member  2006  is attached to the frame member  2000 . In particular, as the bottom housing member  2006  is moved vertically downwards (arrow  2101  in  FIG.  21 B ), the latch  2008  (e.g., a chamfered or otherwise contoured surface of the latch  2008 ) pushes against the top of the second retention feature  2014  of the spring member  2004 . This interaction forces the spring member  2004  to deflect away from the latch  2008  along a direction indicated by arrow  2102 . Once the end of the latch  2008  passes the second retention feature  2014 , the biasing force of the spring member  2004  forces the spring member  2004  back towards the latch  2008  such that the latch  2008  overlaps the second retention feature  2014  to retain the latch  2008  below the second retention feature  2014 . Similar to other interactions with retention features, pushing the latch  2008  past the second retention feature  2014  requires an increased force from the user and may result in a click or other tactile sensation, thus indicating to the user that the bottom housing member  2006  has become engaged. 
     After engaging the latch  2008  and the second retention feature  2014  as shown in  FIGS.  21 A and  21 B , further rotating or twisting of the bottom housing member  2006 , indicated by arrow  2104 ) causes the latch  2008  to move out of engagement with the second retention feature  2014 , slide over the first retention feature  2012  (resulting in another deflection of the spring member  2004  along the direction  2102  in  FIG.  21 B ), and end up positioned at a blind end of the latching region  2002  and below a third retention feature  2106 . The third retention feature  2106  may prevent or inhibit upwards movement of the latch  2008 , while the first retention feature  2012  may remain in contact with the latch  2008  to retain the latch  2008  in the position shown in  FIG.  21 C . The action of sliding the latch  2008  over the first retention feature  2012 , may also produce a tactile click-like feeling that is detectable by the user when twisting the bottom housing member  2006  into the closed configuration. 
       FIGS.  22 A- 22 D  illustrate a schematic view of the frame member  2000  and the bottom housing member  2006 , showing how the latch  2008  disengages from the latching region  2002  and the spring member  2004  when the bottom housing member  2006  is being detached from the frame member  2000 . As shown in  FIG.  22 A , the bottom housing member  2006  is positioned relative to the frame member  2000  such that the latch  2008  is securely maintained in the blind end of the latching region  2002  and below the third retention feature  2106 . In order to detach the bottom housing member  2006 , a user may twist or rotate the bottom housing member  2006 , causing the latch  2008  to slide along the path  2200  in  FIG.  22 B . This motion causes the latch  2008  to contact the first retention feature  2012 , which in turn causes the spring member  2004  to deflect outwards (e.g., along the direction  2102  in  FIG.  21 B ). Because the first retention feature  2012  is biased towards the latch  2008 , the contact between the latch  2008  and the first retention feature  2012  produces a resistance to rotation of the bottom housing member  2006  and potentially produces a tactile click or detent sensation that indicates to the user that the bottom housing member  2006  has been moved out of a securely locked condition. 
     Once the latch  2008  has been moved past the first retention feature  2012 , it may return to the position shown in  FIGS.  21 A- 21 B , wherein the latch  2008  is below and overlaps the second retention feature  2014 . To continue detaching the bottom housing member  2006 , the user pulls the bottom housing member  2006  upwards, along the direction  2202 , which causes the latch  2008  to pull the second retention feature  2014  upwards, thereby deflecting the spring member  2004  along the direction  2016  ( FIG.  20 C ). Once the spring member  2004  is deflected, rotating the bottom housing member  2006  along direction  2204  (e.g., in the direction opposite that indicated in  FIG.  22 B ) causes the latch  2008  to slide over the first retention feature  2012  once again, thereby disengaging the latch  2008  from the spring member  2004  and allowing the bottom housing member  2006  to be removed. The final engagement between the latch  2008  and the first retention feature  2012  may provide a final tactile indication that the bottom housing member  2006  has been detached. 
     The mechanism shown and described with respect to  FIGS.  20 A- 22 D  may include hard-stops formed in the frame member  2000  and/or the spring member  2004  to help guide a user through the attachment and detachment operation. For example, at each position of the bottom housing member  2006 , there may be only one direction in which the bottom housing member  2006  may be moved. Accordingly, the user can determine how to attach and detach the bottom housing member  2006  with a few simple motions. More particularly, the attachment operation may include a push and a twist, and the detachment operation may include a twist (in a first direction), followed by a pull, followed by another twist (in a second, opposite direction), followed by a final pull. 
       FIGS.  23 A- 23 E  illustrate various aspects of another example mechanism for securely retaining a battery door (e.g., a bottom housing member) to a tag.  FIG.  23 A  illustrates a portion of a frame member  2300  that defines a latching region  2302  and a spring member  2304  that extends into the latching region  2302 . The spring member  2304  may be biased to protrude into the latching region  2302 , as depicted in  FIG.  23 A , and may be configured to retract away from the latching region  2302  along the direction  2305 . The frame member  2300  may be an embodiment of the frame member  512 , and may include any or all of the components and may provide any or all of the functionality of the frame member  512  (and may be integrated with the tag  500  or any other tag described herein). For brevity such details may not be repeated here. 
       FIG.  23 B  illustrates a portion of a bottom housing member  2306  that is configured to mate with the frame member  2300  in  FIG.  23 A . The bottom housing member  2306  may be an embodiment of the bottom housing member  516 , and may include any or all of the components and may provide any or all of the functionality of the bottom housing member  516 . For brevity such details may not be repeated here. The bottom housing member  2306  includes a cam latch  2308  that is configured to engage with the frame member  2300  via the latching region  2302  and/or the spring member  2304  to retain the bottom housing member  2306  to the frame member  2300 . The cam latch  2308  may define various surfaces and/or features that engage or otherwise interact with the spring member  2304  to facilitate attachment and detachment of the bottom housing member  2306 . 
       FIG.  23 C  shows the spring member  2304  removed from the frame member  2300 . The spring member  2304  includes the portion that protrudes into the latching region  2302 , as well as a base  2310  that is secured to the frame member  2300 . The spring member  2304  may be a unitary component formed of metal, polymer, or any other suitable material. 
       FIG.  23 D  illustrates the cam latch  2308 , showing the path that the spring member  2304  (e.g., the portion of the spring member  2304  that protrudes into the latching region) would follow along the cam latch  2308  as the bottom housing member  2306  is attached to the frame member  2300 . In particular, as the bottom housing member  2306  is initially engaged with the frame member  2300 , the spring member  2304  moves along the path  2312  and slides over a first cam surface  2314 . After clearing the first cam surface  2314 , the bottom housing member  2306  is rotated such that the spring member  2304  moves along path  2316 , sliding over the first retention feature  2318  and into a blind end  2320  of the cam latch  2308 . At this stage, the first retention feature  2318  and the biasing force of the spring member  2304  retain the spring member  2304  in the blind end  2320 , thereby retaining the bottom housing member  2306  in a closed configuration. 
       FIG.  23 E  illustrates the cam latch  2308 , showing the path that the spring member  2304  would follow along the cam latch  2308  as the bottom housing member  2306  is detached from the frame member  2300 . In particular, the bottom housing member  2306  is rotated so that the spring member  2304  slides over the first retention feature  2318  along path  2322 . Once clear of the first retention feature  2318 , the bottom housing member  2306  is pulled axially away from the frame member  2300 , moving the spring member  2304  along the path  2324  and against a hard-stop defined by the underside of the first cam surface  2314 . The bottom housing member  2306  is then rotated to move the spring member  2304  along the path  2326 , and then finally pulled axially to slide the spring member along the path  2328  and over a second cam surface  2330 , thereby detaching the bottom housing member  2306  from the frame member  2300 . 
     The interactions and engagements between the features of the cam latch  2308  (e.g., the cam surfaces and retention feature) and the spring member  2304  may each require an overcoming force to be applied to the bottom housing member  2306 , and may produce tactile sensations or feedback that are detectable by a user. These forces and feedbacks may help retain the bottom housing member  2306  in desired positions, and also provide useful physical information to the user. 
       FIGS.  24 A- 24 C  illustrate another example spring member and cam latch that may be used with the frame member  2300  and the bottom housing member  2306  described above.  FIG.  24 A  illustrates a spring member  2404  that includes a portion that protrudes into the latching region  2302  ( FIG.  23 A ), as well as a base  2405  that is configured to be secured to the frame member  2300 . The spring member  2404  may be a unitary component formed of metal, polymer, or any other suitable material. 
       FIG.  24 B  illustrates an example cam latch  2408 , which may be used in place of the cam latch  2308  and which may be configured to interface with the spring member  2404  (or another spring member such as the spring member  2304 ).  FIG.  24 B  shows the path that the spring member  2404  (e.g., the portion of the spring member  2404  that protrudes into the latching region) would follow along the cam latch  2408  as the bottom housing member  2306  is attached to the frame member  2300 . In particular, as the bottom housing member  2306  is initially engaged with the frame member  2300 , the spring member  2404  moves along the path  2412  and slides over a first cam surface  2410 . After clearing the first cam surface  2410 , the bottom housing member  2306  is rotated such that the spring member  2404  moves along path  2414 , sliding over a first retention feature  2416  and into a blind end  2418  of the cam latch  2408 . At this stage, the first retention feature  2416  and the biasing force of the spring member  2404  retain the spring member  2404  in the blind end  2418 , thereby retaining the bottom housing member  2306  in a closed configuration. 
       FIG.  24 C  illustrates the cam latch  2408 , showing the path that the spring member  2404  would follow along the cam latch  2408  as the bottom housing member  2306  is detached from the frame member  2300 . In particular, the bottom housing member  2306  is rotated so that the spring member  2404  slides over the first retention feature  2416  along path  2420 . Once clear of the first retention feature  2416 , the bottom housing member  2306  is pulled axially away from the frame member  2300 , moving the spring member  2404  along the path  2422 . The bottom housing member  2306  is then rotated to move the spring member  2404  along the path  2424 , and then finally pulled axially to slide the spring member along a second cam surface  2425 , following the path  2426 , thereby detaching the bottom housing member  2306  from the frame member  2300 . 
     The interactions and engagements between the features of the cam latch  2408  (e.g., the cam surfaces and retention feature) and the spring member  2404  may each require an overcoming force to be applied to the bottom housing member  2306 , and may produce tactile sensations or feedback that are detectable by a user. These forces and feedbacks may help retain the bottom housing member  2306  in desired positions, and also provide useful physical information to the user. 
       FIGS.  25 A- 25 C  illustrate another example spring member and cam latch that may be used with the frame member  2300  and the bottom housing member  2306  described above.  FIG.  25 A  illustrates a spring member  2504  that includes a portion that protrudes into the latching region  2302  ( FIG.  23 A ), as well as a base  2505  that is configured to be secured to the frame member  2300 . The spring member  2504  may be a unitary component formed of metal, polymer, or any other suitable material. 
       FIG.  25 B  illustrates an example cam latch  2508 , which may be used in place of the cam latch  2308  or the cam latch  2408  and which may be configured to interface with the spring member  2504  (or another spring member such as the spring member  2304 ).  FIG.  25 B  shows the path that the spring member  2504  (e.g., the portion of the spring member  2504  that protrudes into the latching region) would follow along the cam latch  2508  as the bottom housing member  2306  is attached to the frame member  2300 . In particular, as the bottom housing member  2306  is initially engaged with the frame member  2300 , the spring member  2504  moves along the path  2512  and slides over a first cam surface  2510 . After clearing the first cam surface  2510 , the spring member  2504  is retained in a retaining area  2514  of the cam latch  2508 . At this stage, the overhanging portion of the first cam surface  2510  and the biasing force of the spring member  2504  (as well as a second cam surface  2516 ) retain the spring member  2504  in the retaining area  2514 , thereby retaining the bottom housing member  2306  in a closed configuration. 
       FIG.  25 C  illustrates the cam latch  2508 , showing the path that the spring member  2504  would follow along the cam latch  2508  as the bottom housing member  2306  is detached from the frame member  2300 . In particular, the bottom housing member  2306  is rotated so that the spring member  2504  slides along the second cam surface  2516  along path  2518 . The bottom housing member  2306  is then pulled axially away from the frame member  2300 , moving the spring member  2504  along the path  2520 , thereby detaching the bottom housing member  2306  from the frame member  2300 . 
     The interactions and engagements between the features of the cam latch  2508  (e.g., the cam surfaces and retention feature) and the spring member  2504  may each require an overcoming force to be applied to the bottom housing member  2306 , and may produce tactile sensations or feedback that are detectable by a user. These forces and feedbacks may help retain the bottom housing member  2306  in desired positions, and also provide useful physical information to the user. 
     As noted above, wirelessly locatable tags may include audio systems that are configured to produce audio outputs. Audio outputs from a wirelessly locatable tag may be used to help a user locate the tag. For example, when a user is attempting to locate a lost tag, the user may use a smartphone to wirelessly command the tag to produce an audible sound such as a beeping or other audible tone (e.g., constant tone, song, etc.). More particularly, the smartphone may send an audio request signal to the tag, which may in turn cause the tag to produce an audible output with an audio system. 
       FIGS.  26 A- 26 B  depict partial cross-sectional views of the tag  500 , showing an example configuration of an audio system, as well as illustrating various operational modes of the audio system. As shown in  FIG.  26 A , the audio system of the tag  500  may include a coil  504  coupled to a top housing member  502 . The coil  504  may include multiple turns of a conductor (e.g., a metal wire) at least partially embedded in a matrix or potting material, such as an epoxy, resin, or other suitable material. The coil  504  may be attached to the inner surface of the top housing member  502  using any suitable method, such as with an adhesive  2600  (as shown), ultrasonic welding, or the like. In some cases, a bobbin or other base structure for the coil  504  may be formed as a unitary structure with the top housing member  502 . For example, a single-piece molded or 3D-printed top housing member  502  may include an integrated bobbin around which a conductor is wound to produce the coil  504 . As another example, conductors forming the coil may be plated onto a bobbin that is integrally formed with the top housing member  502  (e.g., using laser direct structuring or another suitable plating or metallization technique). Other techniques for forming a coil and/or integrating a coil with a top housing member  502  are also contemplated. 
     The coil  504  may be proximate a magnet assembly  506 . The magnet assembly  506  may be any suitable material and may be formed of a single piece of magnetic material, or it may be formed of or include multiple components attached to one another, as shown with respect to  FIG.  27 A . The tag  500  may also include a hard-stop  520  that limits deflection of the top housing member  502 . As described herein, the gap between the top of the hard-stop  520  and the inner surface of the top housing member  502  may be equal to or less than a threshold distance, such as about 500 microns, 400 microns, 300 microns, 200 microns, 100 microns, or 50 microns. 
     The tag  500  may use the coil  504  to move a portion of the top housing member  502  to cause the top housing member  502  to act as a diaphragm to produce audible outputs. For example, when an audio output is required, an appropriate signal is applied to the coil  504  (which is in a magnetic field produced by the magnet assembly  506 ), thereby producing Lorentz forces that act on the coil  504  (indicated by arrows  2602 ). The Lorentz forces on the coil  504  cause the top housing member  502  to move, oscillate, vibrate, or otherwise move (indicated by arrows  2604 ) to produce an audible and optionally tactile output. In some cases, the top housing member  502  locally deflects or deforms to produce the audible and/or tactile output. For example, the central portion of the top housing member  502  may deflect or deform to produce the audible and/or tactile outputs, while other portions of the top housing member  502  (e.g., a peripheral portion that is coupled to the antenna assembly  508 ) remains substantially stationary and/or otherwise does not contribute to the production of sound waves. 
     The audio system, as well as the portion of the top housing member  502  that deflects or deforms to produce audio and/or tactile outputs, may be configured to permit or facilitate the production of audio within a target frequency range. For example, the audio system may be configured to produce sound within a range of about 1 kHz to 4 kHz, 1 kHz to 3 kHz, or any other suitable range. This range may be beneficial due to the relative sensitivity of human hearing to different frequencies, as well as the ability to perceive the location of a sound. For example, human ears are more sensitive to sounds between about 1 kHz to 4 kHz. Also, based at least in part on the distance between a human&#39;s ears, humans can more easily perceive the location of a sound that is at or below 3 kHz (as the location may be perceived without requiring head movement). Accordingly, a range of about 1 kHz to 3 kHz is within a typical range of peak hearing sensitivity and enables simple auditory localization of the tag (e.g., without requiring head movement to perceive the sound&#39;s location). Audible outputs (or ultrasonic outputs, which may be produced by the audio system instead of or in addition to audible outputs) may also be detected by one or multiple microphones on another device (e.g., a smartphone, earbuds, etc.), and that device may use beamforming or other direction-finding techniques to determine or estimate the position of the tag based on the detected audible sounds. In some cases, multiple devices, each with one or more microphone, cooperate to estimate the position of a tag (e.g., by comparing their own position estimates or otherwise cooperating to produce one position estimate). 
     The materials and dimensions of the top housing member  502  may also be configured to facilitate the use of the top housing member  502  as an audio-producing diaphragm. For example, the materials and dimensions may be selected so that the top housing member  502  is sufficiently flexible to allow the top housing member  502  to be deflected and/or deformed by the force produced by the coil  504 . In some cases, the top housing member  502  may be formed of or include a polymer material, such as a polymer, reinforced polymer, carbon fiber, or the like. The top housing member  502  may have a thickness of about 300 microns, 400 microns, 450 microns, 500 microns, 550 microns, or any other suitable thickness. In some cases, a portion of the top housing member  502  that deforms or bends to produce the audible and/or tactile output has a thickness between about 300 and 550 microns, while other portions of the top housing member  502  have different thicknesses (e.g., are thicker or thinner). Other thicknesses and dimension are also possible. 
     In embodiments where the audio system of the tag  500  uses the top housing member  502  as a diaphragm to produce audible and/or tactile outputs, the tag  500  may use the components of the audio system to detect inputs applied to the top housing member  502 .  FIG.  26 B  illustrates the tag  500  as a finger  2606  is applying an input force on the top housing member  502 . This input may correspond to a press or squeeze of the tag  500 , and may result in the top housing member  502  deforming such that the inner or bottom surface of the top housing member  502  moves downward, towards the magnet assembly  506 , as indicated by arrow  2608 . The movement of the top housing member  502  results in the coil  504  moving downward as well, as indicated by arrow  2610 . Because the coil  504  is moving while it is in the magnetic field produced by the magnet assembly  506 , a current may be produced in the coil  504  due to the electromagnetic interaction between a conductor moving in the presence of magnetic flux. This current may be detected by the tag  500  and may indicate that an input has been detected. 
     When the tag  500  detects a current indicative of a threshold amount of motion of the top housing member  502 , the tag  500  may take one or more actions. For example, the tag  500  may initiate a pairing mode (optionally including changing the operation of one or more radios of the tag to facilitate communication with other devices), turn the tag  500  on or off, change a mode of operation of the tag  500 , cause information to be sent via one or more of the tag&#39;s wireless communications systems (e.g., to a remote service, to a mobile phone, etc.), activate or deactivate an audio or tactile output, or the like. 
     The current produced in the coil  504  as a result of a deflection of the top housing member  502  may also be used to provide power to the tag  500  for tag operations and/or to charge the battery  514 . The power may be harvested each time an input is provided, or it may be harvested when certain conditions are met (e.g., when a certain number or frequency of deflections is detected, when the battery is below a threshold charge level, etc.). In some cases, a tag without a battery (or with a fully discharged or dead battery) may be temporarily powered by the user deflecting the top housing member one or more times (e.g., using a number and frequency of deflections that is sufficient to at least momentarily power the tag). If certain conditions are satisfied, the tag may perform one or more actions in response to a repeated deflection. For example, if the battery is dead or missing and a sufficient power threshold is reached from repeated deflections of the top housing member, the tag may send a location report (as described with respect to  FIGS.  2 A- 2 C ), along with an indication that the tag is out of power. 
     As noted above, tags may use other types of input systems or devices may be used to detect inputs to the tag, in addition to or instead of detecting current produced in a coil of an audio system. For example, a dome switch, tactile dome switch, or other electromechanical switching system may be positioned between the top housing member  502  and the magnet assembly  506  (or any other underlying component). When the top housing member  502  is deflected by a user, as shown in  FIG.  26 B , the dome switch or electromechanical switching component may be actuated and the corresponding input detected. In some cases, the magnet assembly  506  may define an opening, and the dome switch or other electromechanical switching system may be positioned in the opening. In such cases, the dome switch or other electromechanical switching system may be attached to the circuit board  510 , the main frame member  512 , or another underlying component. 
     Another type of switching mechanism that may be included in a tag includes conductive contacts attached to the top housing member  502  and an underlying component. For example, a first conductive contact, such as a metal sheet, foil, or other component, may be attached to the interior surface of the top housing member  502  (e.g., at a center of the top housing member  502 , such as aligned with the central opening of the hard-stop  520 ), and one or more second conductive contacts may be positioned below the first conductive contact. When the top housing member  502  is deflected, as shown in  FIG.  26 B , the first conductive contact may contact the one or more second conductive contacts, and the tag may detect the resulting contact, for example, by detecting a change in conductivity between the conductive contacts. As a specific example, the tag may include two second conductive contacts, and the first conductive contact may be configured to conductively couple the two second conductive contacts when the top housing member  502  is depressed. The tag may detect the input by detecting continuity between the two second conductive contacts. Other arrangements of conductive contacts are also contemplated. 
     Other techniques for detecting deflection of the top housing member  502  are also contemplated, including but not limited to capacitive sensors, force sensors, ultrasonic sensors, and optical sensors. Further, other types of input systems may be provided in addition to or in place of input systems that detect deflection of the top housing member  502 . For example, the tag may include buttons, switches, accelerometers (e.g., for detecting shake or tap inputs), or the like. 
       FIG.  27 A  is an exploded view of a portion of the tag  500 . In particular,  FIG.  27 A  shows the coil  504  and an exploded view of the magnet assembly  506  according to one example implementation. The magnet assembly  506  includes a top plate  2700 , an under yoke  2702  (e.g., a metal yoke), and a magnet  2704 . The top plate  2700  and the under yoke  2702  may be formed of or include a metal material such as steel. The top plate  2700  and the under yoke  2702  may cooperate to direct magnetic flux produced by the magnet  2704  along a desired area, and to help reduce leakage flux outside of the tag  500 . Minimizing or otherwise reducing the amount and/or strength of leakage flux (e.g., magnetic flux from the magnet  2704  that extends outside of the housing of the tag  500 ) may help prevent the magnetic flux from interfering with or damaging other objects or devices such as credit cards, magnetometers in other devices, or the like. 
       FIG.  27 B  illustrates a partial cross-sectional view of a portion of the tag  500 , showing example magnetic flux lines in relation to the magnet assembly  506  and the top housing member  502 . The magnet  2704  may produce magnetic flux, while the top plate  2700  and the under yoke  2702  guide or focus the magnetic flux. For example, the top plate  2700  and the under yoke  2702  may be configured to concentrate flux in the gap  2708  where the coil  504  is positioned. By concentrating flux in the gap  2708 , the amount of flux  2706  leaking out beyond the exterior of the tag  500  may be maintained at an acceptable level (e.g., below a threshold level for demagnetizing credit cards). 
     The physical design of the tag  500  may also contribute to the management of leakage flux. For example, the top housing member  502  and the magnet assembly  506  may be configured so that the distance from the magnet assembly  506  (e.g., the top of the magnet assembly) to the exterior surface of the top housing member  502  (e.g., the portion of the exterior surface of the top housing member  502  that is nearest the magnet assembly  506 ) is equal to or greater than a threshold distance. For example, in some cases, the threshold distance is about 1.0 mm, 1.5 mm, 2.0 mm, or any other suitable distance. 
       FIGS.  26 A- 27 B  illustrate an example coil  504  in which conductors (e.g., wires) are at least partially embedded in a potting material, and the potted conductor is attached to the top housing member  502 .  FIGS.  28 A- 28 D  illustrate other example coil configurations that may be used with a wirelessly locatable tag as described herein.  FIG.  28 A  illustrates an example coil  2800  that includes a bobbin  2802  and a conductive coil  2804 . The bobbin  2802  may be a ring-like structure about which the conductive coil  2804  is wound. The bobbin  2802  may be formed from or include a metal (e.g., an aluminum or other metal sheet or foil), polymer, or any other suitable material. The conductive coil  2804  may include a plurality of turns of a conductor such as a wire (e.g., copper wire). 
       FIG.  28 B  is a partial cross-sectional view of a tag, showing how the coil  2800  may be integrated with the components of the tag. In particular, the bobbin  2802  of the coil is attached to the interior or bottom surface of the top housing member  2806  (which may be an embodiment of the top housing member  502 ). The bobbin  2802  may be attached to the top housing member  2806  using an adhesive  2810 , such as an epoxy, or other suitable adhesive or attachment mechanism or technique. The coil  2800  is positioned on the top housing member  2806  such that the conductive coil  2804  is in a magnetic flux field produced by a magnet assembly  2808  (which may be an embodiment of the magnet assembly  506 ). 
       FIG.  28 C  is a partial cross-sectional view of a tag, showing another example of how the coil  2800  may be integrated with the components of the tag. In  FIG.  28 C , the bobbin  2802  is attached to the top housing member  2806  using the adhesive  2810 , as shown in  FIG.  28 B , but also includes a shroud  2812  extending from the top housing member  2806  to the magnet assembly  2808  (or to another component inside the tag). The shroud  2812  may be formed of or include a flexible material, such as a polyester or other polymer film, and may be configured to deform when the tag produces audible and/or tactile outputs by moving the top housing member  2806  with the coil  2800 . The shroud  2812  may be configured to protect the coil  2800  from debris or other contaminants that may affect the physical and/or electrical operation of the coil  2800 . 
       FIG.  28 D  is a partial cross-sectional view of a tag, showing how another coil  2814  may be integrated with the components of the tag. The coil  2814  in  FIG.  28 D  includes a bobbin  2816  and conductive coil  2817 , which are similar to the bobbin  2802  and conductive coil  2804 , except that the bobbin  2816  includes a mounting flange portion  2818  that extends at an angle relative to the portion of the bobbin that is attached to the conductive coil  2817 . The mounting flange portion  2818  may provide a larger contact area between the bobbin  2816  and the top housing member  2806  as compared to the bobbin  2802 . The mounting flange portion  2818  may be secured to the top housing member  2806  via an adhesive  2820 , which may be an epoxy, an adhesive film, a pressure, heat, or temperature sensitive adhesive, or any other suitable adhesive. In some cases a shroud, such as the shroud  2812 , may be included in the implementation shown in  FIG.  28 D . 
     As described above, audible and/or tactile outputs from a tag may be produced with an audio system that uses an electromagnetic coil and a magnet (a system that may be similar to a voice coil motor) to deflect or deform the top housing member of the tag. This is merely one example audio system that may be used to produce such outputs, however, and other audio systems may be used instead of or in place of the coil and magnet arrangements described herein.  FIGS.  29 A- 30    illustrate other example audio systems that may be used to produce audible and/or tactile outputs. 
       FIGS.  29 A- 29 B  illustrate examples in which piezoelectric elements are used to deflect and/or deform a top housing member of a tag to produce audible and/or tactile outputs, using a portion of the top housing member as a speaker diaphragm.  FIG.  29 A  illustrates a portion of an example top housing member  2900 , which may be an embodiment of the top housing member  502 . A piezoelectric element  2902  is attached to the inner or bottom surface of the top housing member  2900  (e.g., using an adhesive or any other suitable fastening technique). The piezoelectric element  2902  may be a piezoelectric unimorph or bimorph. In order to cause the top housing member  2900  to deform or deflect, the tag may apply an electrical signal or current to the piezoelectric element  2902 , thereby causing the piezoelectric element  2902  to bend (indicated by arrows  2904 ). Due to a secure attachment between the piezoelectric element  2902  and the top housing member  2900 , the bending of the piezoelectric element  2902  may cause the top housing member  2900  to deflect or deform (indicated by arrows  2906 ) in a manner that produces audible and/or tactile outputs. 
       FIG.  29 A  illustrates an example in which a single piezoelectric element  2902  is attached to a center of the top housing member  2900 , though this is merely one example implementation of an audio system that uses a piezoelectric element.  FIG.  29 B  illustrates an example in which multiple separate piezoelectric elements  2910  are attached to the inner or bottom surface of the top housing member  2900 . In particular, the piezoelectric elements  2910  are positioned in a corner where the top wall of the top housing member  2900  joins the side wall of the top housing member  2900 . A tag using this arrangement may use two more piezoelectric elements  2910  spaced about the periphery of the top housing member  2900 . In the case where two piezoelectric elements  2910  are used, they may be positioned opposite one another (e.g., with the two piezoelectric elements defining a line through a center of the shape defined by the top housing member  2900 ). The piezoelectric elements  2910  may be unimorph or bimorph piezoelectric elements. 
     In order to cause the top housing member  2900  to deform or deflect, the tag may apply an electrical signal or current to the piezoelectric elements  2910 , thereby causing the piezoelectric elements  2910  to bend (indicated by arrows  2912 ). Due to a secure attachment between the piezoelectric elements  2910  and the top housing member  2900 , the bending of the piezoelectric elements  2910  may cause the top housing member  2900  to deflect or deform (indicated by arrows  2914 ) in a manner that produces audible and/or tactile outputs. 
     The piezoelectric elements  2910  may be mounted remote from the portion of the top housing member that moves the greatest amount during an audible or tactile output, and may use the structure of the top housing member  2900  to amplify the amount of deflection of the piezoelectric elements  2910 . For example, by positioning the piezoelectric elements  2910  in the corners of the top housing member  2900  as shown in  FIG.  29 B , small deflections of the piezoelectric elements  2910  may produce larger deflections at the center of the top housing member  2900 . 
     The piezoelectric elements  2902 ,  2910  may be conductively connected to one or more electronic components and/or circuit elements. The electronic components and/or circuit elements may be positioned on a circuit board (e.g., the circuit board  510 ), and may be configured to provide electrical signals to the piezoelectric elements that cause them to deform in a manner that produces an audible and/or tactile output from the top housing member  2900 . 
       FIG.  30    illustrates another example configuration of an audio system for a tag. In particular,  FIG.  30    illustrates an example top housing member  3000  (which may be an embodiment of the top housing member  502 ) with an audio system  3001  positioned below the top housing member  3000 . The audio system  3001  may be configured to direct sound through one or more openings  3006  that extend through the top housing member  3000 . 
     The audio system  3001  may include an enclosure  3002  that defines an internal volume  3008 . A speaker  3004  may be coupled to the enclosure  3002  or otherwise configured to direct sound into the internal volume  3008 . The internal volume  3008  may have an opening that is aligned with or otherwise communicates with the openings  3006  in the top housing member  3000 . Accordingly, sound from the speaker  3004  may be directed through the internal volume  3008  and out of the openings  3006  (as indicated by arrow  3010 ). The enclosure  3002  may be attached to the top housing member  3000  (e.g., via adhesive, fasteners, ultrasonic welding, etc.), or it may be attached to another component of a tag (e.g., an antenna assembly) and positioned such that it communicates audio through the openings in a top housing member. In tags that include an audio system with a speaker within an enclosure, the tag may employ screens, membranes, water ejection systems, or other systems or techniques to prevent the ingress of water, dust, or other contaminants into the audio system and/or the tag as a whole. 
     For tags in which the top housing member is deflected and/or deformed in order to produce audible and/or tactile outputs, the top housing member may be configured to be sufficiently flexible so that it can be deflected and/or deformed by a voice coil motor, piezoelectric element, or other actuator. In some cases, the top housing member may be a unitary structure formed of a single piece of material. In other cases, it may include multiple components or segments that together define the top housing member.  FIGS.  31 A- 34 C  illustrate several different example top housing members that may be used with wirelessly locatable tags as described herein. The top housing members in  FIGS.  31 A- 34 C  may be embodiments of the top housing member  502 , or any other top housing member described herein. 
       FIGS.  31 A- 31 C  illustrate an example top housing member  3100  that may be formed of a single piece of material. The top housing member  3100  may be formed from a polymer material such as acrylonitrile butadiene styrene (ABS), polyamide, polymethyl methacrylate (PMMA), or any other suitable polymer material (including fiber reinforced polymer materials). In other cases, the top housing member  3100  may be formed of metal. 
       FIG.  31 A  shows the outer surface of the top housing member  3100 , which may define an exterior surface of the tag. As shown, the outer surface of the top housing member  3100  is substantially featureless (e.g., devoid of seams, gaps, grooves, discontinuities, displays, buttons, or other features). In other implementations, however, the outer surface may define or include such features. 
       FIG.  31 B  shows an underside view of the top housing member  3100 . The top housing member  3100  may define reinforcing ribs  3102 , which may be integrally formed with the rest of the top housing member  3100 . For example, the top housing member  3100  may be molded as a single piece with the reinforcing ribs  3102 . The top housing member  3100  may also define a coil attachment region  3104  where a coil (e.g., the coil  504 ) of an audio system may be attached to the top housing member  3100 . The coil attachment region  3104  may be a substantially featureless surface, or it may include grooves, cavities, attachment elements, or other features. 
       FIG.  31 C  is a cross-sectional view of the top housing member  3100 , viewed along line  31 C- 31 C in  FIG.  31 A . As shown, the top housing member  3100  may not have a uniform thickness. For example, in some cases a central portion of the top housing member  3100  (e.g., at and/or around the coil attachment region  3104 ) may be thinner than a sidewall portion of the top housing member  3100 . This may provide increased flexibility at the area of the top housing member  3100  that needs to deflect and/or deform to produce audible and/or tactile outputs. 
       FIGS.  32 A- 32 C  illustrate an example top housing member  3200  that may include multiple components.  FIG.  32 A  shows the outer surface of the top housing member  3200 , which may define an exterior surface of the tag. The top housing member  3200  may include a peripheral member  3202 , a central member  3204 , and a compliant member  3206 . The peripheral member  3202  may define a peripheral wall and a top wall, with the top wall defining an opening in which the central member  3204  may be at least partially positioned. The peripheral wall of the peripheral member  3202  may define a peripheral side wall (and thus the exterior peripheral side surface) of the tag. 
     The compliant member  3206  may be formed from a more flexible material than the peripheral member  3202  and the central member  3204 . For example, the peripheral member  3202  (which may define a side wall of the top housing member  3200 ) and the central member  3204  (which may define a top outer surface of the top housing member  3200 ) may be formed from a first polymer material such as an ABS, PMMA, and the compliant member  3206  may be formed from a second polymer material that is more flexible than the first polymer material, such as silicone, thermoplastic polyurethane (TPU), or the like. The compliant member  3206  may be configured to allow the central member  3204  to move more freely relative to the peripheral member  3202  than would occur if the central and peripheral members were a unitary structure (such as the top housing member  3100 ). 
       FIG.  32 B  shows an underside view of the top housing member  3200 . The top housing member  3200  may define reinforcing ribs  3208 , which may be integrally formed with the peripheral member  3202 . The central member  3204  may define a coil attachment region  3210 , which may be similar to the coil attachment region  3104 , described above. 
       FIG.  32 C  is a cross-sectional view of the top housing member  3200 , viewed along line  32 C- 32 C in  FIG.  32 A . As shown, the portion of the compliant member  3206  that is visible on the outer surface of the top housing member  3200  may only be a part of the compliant member  3206 . More particularly, the compliant member  3206  may extend along a portion of the inner or bottom surface of the central member  3204 , and may mechanically couple the central member  3204  to the peripheral member  3202 . The compliant member  3206  may define an opening that exposes the coil attachment region  3210  so that the coil can be attached directly to the central member  3204 , thereby directly transferring force to the central member  3204 . In some cases, the part of the compliant member  3206  that is exposed adjacent the outer surfaces of the central and peripheral members are flush with the central and peripheral members, as illustrated in  FIG.  32 C . In other cases, the part of the compliant member  3206  that is exposed may be recessed or proud relative to the peripheral and central members.  FIG.  33 C , for example, illustrates an embodiment in which a compliant member is recessed relative to the central and peripheral members. 
     The top housing member  3200  may be formed by a co-injection molding or insert molding technique, where the central and peripheral members are formed first (and optionally inserted into a second mold after they are formed), and then the material of the compliant member  3206  is injected into the mold and against the central and peripheral members. This may cause the compliant member to be formed into the target shape, as well as to secure the material of the compliant member to the central and peripheral members (e.g., via chemical and/or adhesive bonding between the materials, and/or via mechanical interlocking between the components). 
     The decreased stiffness of the compliant member  3206  relative to the central and peripheral members may increase the amount of movement of the central member that is achieved for a given coil force, as compared to a single-piece top housing member. This, in turn, may improve the efficiency of the tag with respect to producing audible and/or tactile outputs. Further, the lower force requirement may allow the use of smaller coils, magnets, piezoelectric elements, or other force-producing elements of an audio system. Additionally, embodiments of top housing members that use separate central and peripheral members may employ a different mode of deformation or deflection than single-piece housing members. That is, the central member  3204  itself deforms less than the central region of a single-piece top housing member, and instead moves more vertically (e.g., like a plate moving along a vertical path). Stated another way, whereas a single-piece top housing member may be deformed in a bulge-like shape to produce audible and/or tactile outputs, the central member  3204  of the top housing member  3200  may remain substantially undeformed while it is moved vertically up and down (e.g., in a largely or entirely translational movement) to produce such outputs. In cases where the central member of the top housing member is separate from the peripheral member, the central member may be thicker and/or stiffer than a central member of a single-piece top housing member. 
       FIGS.  33 A- 33 C  illustrate another example top housing member  3300  that may include multiple components.  FIG.  33 A  shows the outer surface of the top housing member  3300 , which may define an exterior surface of the tag. The top housing member  3300  may define a peripheral member  3302 , a central member  3304 , and a compliant member  3306 . The peripheral member  3302  may define a peripheral wall and a top wall, with the top wall defining an opening in which the central member  3304  may be at least partially positioned. The peripheral wall of the peripheral member  3302  may define a peripheral side wall (and thus the exterior peripheral side surface) of the tag. 
     The compliant member  3306  may be formed from a more flexible material than the peripheral member  3302  and the central member  3304 . For example, the peripheral member  3302  (which may define a side wall of the top housing member  3300 ) and the central member  3304  (which may define a top outer surface of the top housing member  3300 ) may be formed from a first polymer material such as an ABS, PMMA, and the compliant member  3306  may be formed from a second polymer material that is more flexible than the first polymer material, such as silicone, thermoplastic polyurethane (TPU), or the like. The compliant member  3306  may be configured to allow the central member  3304  to move more freely relative to the peripheral member  3302  than would occur if the central and peripheral members were a unitary structure (such as the top housing member  3100 ). 
       FIG.  33 B  shows an underside view of the top housing member  3300 . The top housing member  3300  may define reinforcing ribs  3308 , which may be integrally formed with the peripheral member  3302 . The central member  3304  may define a coil attachment region  3310 , which may be similar to the coil attachment region  3104 , described above. 
       FIG.  33 C  is a cross-sectional view of the top housing member  3300 , viewed along line  33 C- 33 C in  FIG.  33 A . As shown, the portion of the compliant member  3306  that is visible on the outer surface of the top housing member  3300  may only be a part of the compliant member  3306 . More particularly, the compliant member  3306  may extend along a portion of the inner or bottom surface of the central member  3304 , and may mechanically couple the central member  3304  to the peripheral member  3302 . The compliant member  3306  may define an opening that exposes the coil attachment region  3310  so that the coil can be attached directly to the central member  3304 , thereby directly transferring force to the central member  3304 . The part of the compliant member  3306  that is exposed may be recessed relative to the peripheral and central members. 
     The top housing member  3300  may be formed by a co-injection molding or insert molding technique, as described above with respect to the top housing member  3200 . Further, like the top housing member  3200 , the top housing member  3300  may be configured to produce audible and/or tactile outputs using substantially linear movement (with no or only nominal deformation) of the central member  3304 , rather than a bending or deformation mode (as is the case with the unitary top housing member  3100 ). In some cases, the central member  3304  may translate relative to the peripheral member  3302  to produce the audible output. 
       FIGS.  34 A- 34 C  illustrate another example top housing member  3400  that may include multiple components.  FIG.  34 A  shows the outer surface of the top housing member  3400 , which may define an exterior surface of the tag. The top housing member  3400  may define a peripheral member  3402 , and a compliant member  3406 . The compliant member  3406  defines a central region of the top housing member  3400 , which is part of the exterior surface of the top housing member  3400  and thus part of the exterior surface of the device that uses the top housing member  3400 . The compliant member  3406  may be formed of similar materials as the compliant members  3206 ,  3306  (e.g., silicone, thermoplastic polyurethane (TPU), or the like). 
       FIG.  34 B  shows an underside view of the top housing member  3400 . The top housing member  3400  may define reinforcing ribs  3408 , which may be integrally formed with the peripheral member  3402 . The top housing member  3400  may also include a central member  3404  that is below the compliant member  3406 . The central member  3404  may be formed from a more rigid material than the compliant member (and may be the same material as the peripheral member  3402 ). The central member  3404  may define a coil attachment region  3410 , which may be similar to the coil attachment region  3104 , described above. By providing the central member  3404  below the compliant member  3406 , and leaving the central member  3404  exposed on the interior side of the top housing member  3400 , the coil can attach directly to the relatively central member  3404  and use the stiffness of the central member  3404  to more efficiently translate the movement of the coil into vertical motion of the central member of the top housing member  3400  (as compared, for example, to a top housing member  3400  without the central member). The vertical motion may correspond to a translation of the central member  3404  relative to the peripheral member  3402 . 
       FIG.  34 C  is a cross-sectional view of the top housing member  3400 , viewed along line  34 C- 34 C in  FIG.  34 A . As shown, the compliant member  3406  defines substantially all of the top exterior surface of the top housing member  3400 , and the central member  3404  does not define any part of the exterior of the top housing member  3400 . 
     The top housing member  3400  may be formed by a co-injection molding or insert molding technique, as described above with respect to the top housing member  3200 . Further, like the top housing member  3200 , the top housing member  3400  may be configured to produce audible and/or tactile outputs using substantially linear movement (with no or only nominal deformation) of the central member  3404  (and the overlying part of the compliant member  3406 ), rather than a bending or deformation mode (as is the case with the unitary top housing member  3100 ). 
     The wirelessly locatable tags described above are described with respect to one example form factor and configuration. For example,  FIGS.  3 A- 34 C  illustrate example wirelessly locatable tags that have a generally round, puck-shaped design, with a battery door (e.g., bottom housing member) that can be detached from the rest of the tag to allow the battery to be swapped. However, the same or similar systems and functions described with respect to the generally puck-shaped configurations may be incorporated into tags having other form factors.  FIGS.  35 A- 58 C  illustrate several example wirelessly locatable tags having various different form factors, battery cavity access systems, housing components, and the like. 
       FIG.  35 A  illustrates an example tag  3500  that uses a battery access mechanism instead of a removable battery door to provide access to a battery cavity. The tag  3500  includes a body portion  3502  and a peripheral portion  3504 . The body portion  3502  has a generally round, puck-shaped configuration, and the peripheral portion  3504  extends around the periphery of the body portion  3502 . The body portion  3502  may define the top and bottom surfaces of the tag  3500 , while the peripheral portion  3504  defines the peripheral side surface(s) of the tag  3500 . 
     The peripheral portion  3504  may be manipulated relative to the body portion  3502  to cause a battery cavity to be exposed. For example, a user may rotate the peripheral portion  3504  about the body portion  3502  while holding the body portion  3502  stationary (as indicated by arrow  3506 ). As shown in  FIG.  35 B , this manipulation may cause the body portion  3502  to move axially out from the inner area of the peripheral portion  3504  (as indicated by arrow  3508 ), thereby exposing a battery cavity  3512  to allow a battery  3510  to be removed and/or replaced.  FIG.  35 C  shows the battery  3510  being removed from the battery cavity  3512 . The tag  3500  may be closed by rotating the peripheral portion  3504  about the body portion  3502  (while holding the body portion  3502  stationary) in the direction opposite that which is used to open the tag  3500 . When the tag  3500  is closed, the peripheral portion  3504  may help retain the battery  3510  in the battery cavity  3512 . 
       FIGS.  35 D- 35 E  are partial cross-sectional views of the tag  3500 , viewed along line  35 D- 35 D in  FIG.  35 A . These cross-sections are simplified for clarity, and do not show all components of the tag  3500 .  FIG.  35 D  shows the tag  3500  in a closed configuration, while  FIG.  35 E  shows the tag  3500  in an open configuration (corresponding to the configuration shown in  FIG.  35 C ). The top and bottom surfaces of the body portion  3502  may stay the same distance apart when the body portion  3502  is extended as shown in  FIG.  35 E . Thus, for example, when the peripheral portion  3504  is twisted to cause the body portion  3502  to extend axially and expose the battery cavity  3512 , a recess  3514  is formed due to the movement of the body portion  3502 . 
       FIG.  36 A  is an exploded view of a portion of tag  3609 , illustrating details of a mechanism that facilitates the opening and closing of the tag  3609  in a manner similar to that of the tag  3500  shown in  FIGS.  35 A- 35 E . The mechanism shown in  FIGS.  36 A- 36 B  causes the body portion to expand or extend such that the bottom surface of the body portion remains in place relative to the peripheral portion, and only the top surface moves upwards to expose the battery cavity. 
     The tag  3609  includes an upper body portion  3603 , which defines a battery cavity  3607 , and a lower body portion  3604 . Together, the upper and lower body portions  3603 ,  3604  may define some or all of a body portion of the tag  3609 . The upper body portion  3603  may define a top exterior surface of the tag  3609  while the lower body portion  3604  defines a bottom exterior surface of the tag  3609 . The lower body portion  3604  may include and/or support device components  3610 . The device components  3610  may include circuit boards, circuit elements, processors, memory, sensors, radio circuitry (including antennas) for various wireless communications (e.g., UWB, WiFi, Bluetooth, etc.), or the like. Indeed, the device components  3610  may include any of the components that are used to provide the functions of a wireless tag as described herein. 
     The upper body portion  3603  includes guide pins  3601  extending from a peripheral side of the upper body portion  3603 . The guide pins  3601  may engage first guide slots  3602  of a guide ring  3600 . The first guide slots  3602  may extend through the guide ring  3600  (as shown), or they may be blind channels. 
     The guide ring  3600  may be attached to the peripheral portion  3605  such that the peripheral portion  3605  and the guide ring  3600  rotate together when a rotational force is applied to the peripheral portion  3605  (while the body portion is held stationary). The guide ring  3600  may be attached to the peripheral portion  3605  in any suitable way, such as with adhesives, clips, fasteners, springs, mechanical interlocks, or the like. 
     The lower body portion  3604  may define second guide slots  3606  that also engage the guide pins  3601  of the upper body portion  3603 . Whereas the first guide slots  3602  are oriented at a slant relative to the axis of the tag  3609 , the second guide slots  3606  are parallel to the axis. When assembled, the interaction between the guide pins  3601 , the first guide slots  3602 , and the second guide slots  3606  cause the upper body portion  3603  to move axially, relative to the peripheral portion  3605  and the lower body portion  3604 , when the peripheral portion  3605  is rotated about the body portion. For example, the rotational movement of the guide ring  3600  (caused by rotational movement of the peripheral portion  3605 ) forces the guide pins  3601  to slide within the first guide slots  3602 , while the second guide slots  3606  prevent the upper body portion  3603  from rotating. The combined effect of the interactions between the guide pins  3601  and the first and second guide slots  3602 ,  3606  causes the upper body portion  3603  to move axially upward (relative to the orientation in  FIG.  36 A ), thereby exposing the battery cavity  3607 . In some cases, the first and/or second guide slots  3602 ,  3606  may include bumps, catches, protrusions, or other features that provide a tactile indication that the tag is fully open or fully closed. Such features may also help retain the tag in a fully open or closed position.  FIG.  36 B  shows a partial cross-sectional view of the tag  3609 , illustrating how the lower body portion  3604  remains substantially flush with (or otherwise does not move relative to) the bottom edge of the peripheral portion  3605  when the upper body portion  3603  is extended axially upwards to expose the battery cavity  3607 . 
     The tag  3609  may include conductors that conductively couple a battery contact (that connects to the battery terminals of the battery) to the device components  3610 . The conductors may be flexible to accommodate the motion between the upper body portion  3603  and the rest of the tag  3609 . In other cases, sliding electrical contacts, which may be similar to slip rings, may be used to conductively couple the battery connector to device components on a different structure of the tag  3609 . A similar battery connector structure may be used for the tag  3500  as well. 
       FIGS.  37 A- 37 C  illustrate another example tag  3700  that uses a battery access mechanism instead of a removable battery door to provide access to a battery cavity. The tag  3700  includes a body portion  3702  and a peripheral portion  3704 . The body portion  3702  has a generally round, puck-shaped configuration, and the peripheral portion  3704  extends around the periphery of the body portion  3702 . The body portion  3702  may define the top and bottom surfaces of the tag  3700 , while the peripheral portion  3704  defines the peripheral side surface(s) of the tag  3700 . 
     The peripheral portion  3704  may be manipulated relative to the body portion  3702  to cause a battery cavity to be exposed. For example, a user may push the body portion  3702  upward relative to the peripheral portion  3704 , as illustrated by the arrows  3706 . This may be achieved by a user pushing on the body portion  3702  from the bottom (e.g., with a thumb), while pulling down on the peripheral portion  3704 . 
     As shown in  FIG.  37 B , this manipulation may cause the body portion  3702  to move axially upwards relative to the peripheral portion  3704 , thereby revealing the battery cavity  3710 .  FIG.  37 C  shows the battery  3712  being removed from the battery cavity. Like the tag  3500 , the peripheral portion  3704  may help retain the battery  3712  in the battery cavity  3710  when the tag  3700  is closed. 
     The tag  3700  may include guide mechanisms or features (e.g., guide pins and guide slots that engage the guide pins) to constrain the movement of the body portion  3702  relative to the peripheral portion  3704 . For example, the guide mechanisms or features may guide the body portion  3702  so that it moves linearly relative to the peripheral portion  3704  and does not rotate relative to the peripheral portion  3704 . The guide mechanisms or features may also limit the axial travel of the body portion  3702  relative to the peripheral portion  3704  and prevent them from separating from one another. Further, the guide mechanisms or features may include detents, latches, catches, or other features that tactilely indicate when the body portion  3702  is in a fully open or fully closed position, and also retain the body portion  3702  in a fully open or fully closed position. 
       FIGS.  38 A- 38 C  illustrate another example tag  3800  that uses a battery access mechanism instead of a removable battery door to provide access to a battery cavity. The tag  3800  includes a body portion  3802  and a peripheral portion  3804 . The body portion  3802  has a generally round, puck-shaped configuration, and the peripheral portion  3804  extends around the periphery of the body portion  3802 . The body portion  3802  may define the top and bottom surfaces of the tag  3800 , while the peripheral portion  3804  defines the peripheral side surface(s) of the tag  3800 . 
     The peripheral portion  3804  may be manipulated relative to the body portion  3802  to cause a battery cavity to be exposed. For example, a user may pivot the peripheral portion  3804  relative to the body portion  3802 , as illustrated by the arrows  3806 . This may be achieved by a user grasping the peripheral portion  3804  and twisting the peripheral portion  3804  about a diametrical axis of the body portion  3802 , while holding the body portion  3802  stationary (or any equivalent manipulations). 
     As shown in  FIG.  38 B , this manipulation may cause the peripheral portion  3804  to pivot relative to the body portion  3802 , thereby revealing the battery cavity  3810 .  FIG.  38 C  shows the battery  3812  being removed from the battery cavity. Like the tag  3500 , the peripheral portion  3804  may help retain the battery  3812  in the battery cavity  3810  when the tag  3800  is closed. 
     The tag  3800  may include a pivoting mechanism that pivotally couples the peripheral portion  3804  to the body portion  3802 . The pivoting mechanism may include, for example, a complementary set of pins and receptacles (on the peripheral portion  3804  and body portion  3802 ) that engage to pivotally couple the components together. The tag  3800  may also include travel limiting features (such as lips, flanges, pins and slots, latches, catches, or other interacting structures) that limit the amount and/or direction that the peripheral portion  3804  can pivot about the body portion  3802 . The tag  3800  may also include detents, latches, catches, or other features that tactilely indicate when the peripheral portion  3804  is in a fully open or fully closed position, relative to the body portion  3802 , and also retain the peripheral portion  3804  in a fully open or fully closed position. 
       FIGS.  39 A- 39 C  illustrate another example tag  3900  that uses a battery access mechanism instead of a removable battery door to provide access to a battery cavity. The tag  3900  includes a body portion  3902  and a peripheral portion  3904 . The body portion  3902  has a generally round, puck-shaped configuration, and the peripheral portion  3904  extends around the periphery of the body portion  3902 . The body portion  3902  may define the top and bottom surfaces of the tag  3900 , while the peripheral portion  3904  defines the peripheral side surface(s) of the tag  3900 . 
     The peripheral portion  3904  may be formed from a compliant material that is attached to the body portion  3902  along a seam  3903 , as shown in  FIG.  39 B . The peripheral portion  3904  may have a bistable configuration. In a first stable position ( FIG.  39 A ) the peripheral portion  3904  covers the sides of the body portion  3902  and covers the battery cavity  3910  ( FIG.  39 B ), thereby retaining the battery  3912  ( FIG.  39 B ) in the battery cavity. In a second stable configuration, the peripheral portion  3904  is deflected or deformed downward and, while still attached to the body portion  3902  at the seam  3903  (and without requiring an applied force to maintain the peripheral portion  3904  in the second stable configuration), the battery cavity  3910  is exposed to allow the battery  3912  to be removed and/or replaced. In some cases, instead of being bistable, the peripheral portion  3904  may be biased towards the closed configuration ( FIG.  39 A ), and the user must hold the peripheral portion  3904  in the open configuration while replacing the battery. 
     The peripheral portion  3904  may be moved to the second configuration by a user applying a rolling or peeling force on the peripheral portion  3904 .  FIGS.  39 A- 39 B  show an example rolling force, indicated by arrows  3906 , that may be applied to the peripheral portion  3904  to expose the battery cavity  3910 . In order to close the tag  3900 , a user may apply a force to the peripheral portion  3904  in an opposite direction (if the peripheral portion  3904  is bistable), or simply cease holding the peripheral portion  3904  open (if the peripheral portion  3904  is biased to the closed configuration). 
     The peripheral portion  3904  may be formed from or include a polymer material, such as an elastomeric material. The material and the shape of the peripheral portion  3904  may cooperate to produce the bistable (or non-bistable) configurations described above. The peripheral portion  3904  may be attached to the body portion  3902  (at the seam  3903 ) in any suitable way. For example, the peripheral portion  3904  may be mechanically engaged with the body portion  3902 . In some cases, the peripheral portion  3904  and the body portion  3902  may be insert molded or co-molded to form a mechanical interlock (and optionally chemical or adhesive bond) that attaches the peripheral portion  3904  to the body portion  3902 . 
       FIGS.  40 A- 40 C  illustrate another example tag  4000  that uses yet another housing configuration to provide access to a battery cavity. The tag  4000  includes a first body portion  4002  and a second body portion  4004 . The first and second body portions  4002 ,  4004  may be substantially similar in shape and size. The first body portion  4002  may define a top surface and about half of a peripheral side surface of the tag  4000 , while the second body portion  4004  may define a bottom surface and the other half of the peripheral side surface of the tag  4000 . 
     The first and second body portions  4002 ,  4004  may be separated from one another to reveal a battery cavity  4010  ( FIG.  40 C ) and allow the battery  4012  to be swapped. Both the first and the second body portions  4002 ,  4004  may define part of the battery cavity  4010 . 
     The first and second body portions  4002 ,  4004  may be separated by a press-and-twist interaction, whereby the user must apply an axial force (represented by arrows  4006 ) prior to and/or while applying a twisting force (represented by arrow  4008 ). The user may then separate the first and second body portions  4002 ,  4004 , as shown in  FIG.  40 B . The tag  4000  may include features such as latches, cam latches, springs, channels, protrusions, or the like to releasably engage the first and second body portions  4002 ,  4004  and allow them to be separated as shown in  FIGS.  40 A- 40 B . Some examples of such features and/or mechanisms are described above with respect to  FIGS.  12 A- 12 C and  14 A- 25 C . Accordingly, for brevity, their details may not be repeated here. 
     Wirelessly locatable tags may have form factors other than round, puck-shaped tags as shown in various figures of the instant application. Even where other form factors are used, similar features, functions, mechanisms, and systems may be included in the tags.  FIGS.  41 A- 41 C  illustrate an example wirelessly locatable tag  4100  that has a generally lozenge-shaped appearance, as compared to the circular, puck-shaped tags described elsewhere herein. 
     The tag  4100  may include a first housing member  4102  and a second housing member  4104 . The second housing member  4104  may be removable from the remainder of the tag  4100 , and may be removed (e.g., by pulling the second housing member  4104  along the direction  4106 ) to expose a battery cavity and battery to facilitate battery replacement.  FIG.  41 B  illustrates the tag  4100  with the second housing member  4104  detached from the tag  4100  and exposing the battery cavity  4110 . The tag  4100  may include a frame member  4114 . The frame member may at least partially define the battery cavity  4110 , and may support other tag components such as a circuit board, antennas, an audio system, and the like. 
     The tag  4100  may also include a latch mechanism  4116  that releasably retains the second housing member  4104  to the frame member  4114 . The latch mechanism  4116  may include an outwardly-biased latching feature that engages a recess, cavity, or other feature in the second housing member  4104  to retain the second housing member  4104  to the frame member  4114 , while also permitting the second housing member  4104  to be removed by a user. The latch mechanism  4116  may include a locking mechanism or component such that a user cannot detach the second housing member  4104  simply by pulling on it. For example, the tag  4100  may include a button that must be pushed in order to allow the latch mechanism  4116  to release the second housing member  4104 . 
       FIG.  41 C  is a partial cross-sectional view of the tag  4100 , viewed along line  41 C- 41 C in  FIG.  41 A .  FIG.  41 C  shows the battery  4112  in the battery cavity  4110  defined by the frame member  4114 .  FIG.  41 C  further illustrates how the latch mechanism  4116  may engage a recess or other feature in the second housing member  4104 . The latch mechanism  4116  and the second housing member  4104  may be configured so that the latch mechanism  4116  deflects downward in response to the second housing member  4104  being attached to the tag. For example, the top of the latch mechanism  4116  may be rounded, chamfered, or otherwise define an interface surface that, when contacted by the second housing member  4104 , forces the latch mechanism  4116  to deflect in a way that permits the second housing member  4104  to be fully attached. 
       FIG.  41 C  also illustrates a circuit board  4122  and an audio system  4120  in an area that is at least partially covered by the first housing member  4102 . The circuit board  4122  may include circuit elements, processors, memory, conductors, sensors, antennas, or any other components. Such components may also be positioned elsewhere in or on the tag  4100 . For example, antennas may be integrated with the frame member  4114  in a manner similar to the antenna assembly  508 , described above. 
     The audio system  4120  may operate similar to other audio systems described herein. For example, a coil may be attached to an interior surface of the first housing member  4102 , and a magnet may provide a magnetic field to allow the coil to operate as a speaker. By passing a signal (e.g., current) through the coil, a portion of the first housing member  4102  can move in a manner similar to a speaker diaphragm. Further, the audio system  4120  may be used to produce tactile outputs that a user can feel when touching the first housing member  4102 . Of course, other types of audio systems and/or tactile output generators may be used instead of or in addition to the audio system  4120 . 
       FIGS.  42 A- 42 B  illustrate another example wirelessly locatable tag  4200  that has a generally lozenge-shaped form factor. The tag  4200  includes a first housing member  4202  that defines all or substantially all of a top surface and part of the peripheral surface of the tag  4200 . The tag  4200  also includes a second housing member  4204  that defines part of (e.g., approximately half of) a bottom surface of the tag  4200  and part of the peripheral surface of the tag  4200 . The second housing member  4204  may not be intended to be removed by a user of the tag  4200 . The tag  4200  may also include a third housing member  4206 , which may also define part of (e.g., approximately half of) the bottom surface of the tag  4200  and part of the peripheral surface of the tag  4200 . 
     The third housing member  4206  may be removable to provide access to a battery cavity. For example,  FIG.  42 A  illustrates the third housing member  4206  removed from the rest of the tag  4200 . The third housing member  4206  may define at least part of a battery cavity  4210  for a battery  4212 . Features of the third housing member  4206  may engage corresponding features of the first and/or second housing members  4202 ,  4204 , or any other component of the tag  4200  (e.g., a frame member), to retain the third housing member  4206  to the tag  4200  while also allowing it to be removed for battery replacement. Such features may include clips, latches, detents, or the like. The third housing member  4206  may be removed from the tag  4200  by prying with a fingernail, tool, or other implement inserted in a gap between the third housing member  4206  and another part of the tag  4200 . 
     In other respects, such as the component set and the function and arrangement of such components (including circuit boards, audio systems, antennas, etc.), the tag  4200  may be substantially similar to the tag  4100 . Further, the tag  4200  may include any of the components and/or provide any of the features of any tag described herein. 
       FIGS.  43 A- 43 C  illustrate another example wirelessly locatable tag  4300  that has a generally lozenge-shaped form factor. The tag  4300  includes a first housing member  4302  that defines all or substantially all of a top surface and part of the peripheral surface of the tag  4300 . The tag  4300  also includes a second housing member  4304  that defines substantially all or part of a bottom surface of the tag  4300  and part of the peripheral surface of the tag  4300 . The second housing member  4304  may be removable from the first housing member  4302  and may define one or more battery cavities. 
     The second housing member  4304  may act as a battery tray for the tag  4300 . The second housing member  4304  may be slidably engaged with the tag  4300 . For example, the second housing member  4304  may engage rails or slots of the first housing member  4302  (or defined by any other component of the tag  4300 ). The second housing member  4304  may be removed by pulling the second housing member  4304  outwardly (e.g., in a direction parallel to the long axis of the lozenge-shaped tag  4300 ). The tag  4300  may include retention features (e.g., clips, latches, locking mechanisms, etc.) that retain the second housing member  4304  in a closed configuration during use, and help prevent accidental removal of the second housing member  4304 . 
       FIG.  43 B  illustrates the tag  4300  with the second housing member  4304  removed from the tag  4300 . The second housing member  4304  defines two battery cavities  4310  for receiving two batteries  4312 . 
       FIG.  43 C  is a partial cross-sectional view of the tag  4300 , viewed along line  43 C- 43 C in  FIG.  43 A .  FIG.  43 C  shows the batteries  4312  in the battery cavities  4310  defined by the second housing member  4304 .  FIG.  43 C  also illustrates a circuit board  4316  and an audio system  4314 , both of which may be mounted on a frame member  4315 . The frame member, circuit board, and audio system may all have the same or similar components and may provide the same or similar functions to the other frame members, circuit boards, and audio systems described herein, and for brevity their details may not be repeated here. In other respects, such as the component set and the function and arrangement of such components (including circuit boards, audio systems, antennas, etc.), the tag  4300  may be substantially similar to other tags described herein. 
       FIGS.  44 A- 44 C  illustrate another example wirelessly locatable tag  4400  that has a generally lozenge-shaped form factor. The tag  4400  includes a first housing member  4402  that defines part of a top surface, part of a bottom surface, and part of the peripheral surface of the tag  4400 . The tag  4400  also includes a second housing member  4404  that defines the remaining parts of the top surface, bottom surface, and peripheral surface of the tag  4400 . The second housing member  4404  may be removable from the first housing member  4402  and may define a battery cavity. 
       FIG.  44 B  shows the tag  4400  with the second housing member  4404  detached from the first housing member  4402 . The second housing member  4404  may define a battery cavity  4410  for receiving the battery  4412 . The first housing member  4402  may define a ledge  4406  that engages the second housing member  4404  to releasably retain the first and second housing members together. The ledge  4406  may include latches, catches, protrusions, channels, recesses, or other features that engage corresponding features on the second housing member  4404  to hold the first and second housing members together, while also allowing them to be separated by a user to access the battery cavity  4410  to remove and/or replace the battery. Such features may be integral with the ledge  4406  and the second housing member  4404 , or they may be separate components attached to the ledge  4406  and/or the second housing member  4404 . 
       FIG.  44 C  is a partial cross-sectional view of the tag  4400 , viewed along line  44 C- 44 C in  FIG.  44 A .  FIG.  44 C  shows the battery  4412  in the battery cavity  4410  defined by the second housing member  4404 .  FIG.  44 C  shows how a protrusion defined by or otherwise attached to the ledge  4406  may engage a corresponding recess along an interior surface of the second housing member  4404 . The protrusion and recess may retain the first and second housing members  4402 ,  4404  together, while allowing them to be detached if a user applies a sufficient force to overcome the retention force produced by the protrusion and recess (e.g., by pulling them apart). 
       FIG.  44 C  also illustrates a circuit board  4416  and an audio system  4414  within an internal cavity defined by the first housing member  4402 . The tag  4400  may also include battery connectors  4418 ,  4420  ( FIG.  44 B ) that contact the positive and negative terminals of the battery and provide power from the battery to the circuit board  4416  and/or other electrical components of the tag  4400 . The circuit board and audio system may all have the same or similar components and may provide the same or similar functions to the other circuit boards and audio systems described herein, and for brevity, their details may not be repeated here. In other respects, such as the component set and the function and arrangement of such components (including circuit boards, audio systems, antennas, etc.), the tag  4400  may be substantially similar to other tags described herein. 
       FIGS.  45 A- 45 B  illustrate another example wirelessly locatable tag  4500  that has a generally lozenge-shaped form factor. The tag  4500  includes a removable housing member  4506  that can be removed from the rest of the tag  4500  to provide access to a battery cavity  4510 . The tag  4500  may include other housing members, such as a first housing member  4502 , a second housing member  4504 , and a third housing member  4505 , which may be configured as non-user-removable housing members. In some cases, more or fewer housing members may be used. For example, a single housing member may be used instead of the separate first and second housing members. 
       FIG.  45 B  shows the tag  4500  with the second housing member  4504  detached from the tag  4500 . The tag  4500  may include a frame member  4508 , and the battery cavity  4512  may be defined in the frame member  4508 . The first, second, and third housing members  4502 ,  4504 , and  4505  may be attached to the frame member  4508 , such as via clips, adhesives, ultrasonic welding, or the like. The removable housing member  4506  may be releasably retained to the frame member  4508  via clips, latches, detents, channels, recesses, or any other suitable retention feature that retains the removable housing member  4506  to the frame (or other component of the tag  4500 ) while allowing it to be detached if a user applies a sufficient force to overcome the retention force provided by the features. 
     In other respects, such as the component set and the function and arrangement of such components (including circuit boards, audio systems, antennas, etc.), the tag  4500  may be substantially similar to other tags described herein. 
       FIGS.  46 A- 46 B  illustrate another example wirelessly locatable tag  4600  that has a generally lozenge-shaped form factor. The tag  4600  includes a first housing member  4602  that defines all or substantially all of a top surface and a bottom surface, and part of the peripheral surface of the tag  4600 . The tag  4600  also includes a second housing member  4604  that defines a remaining the remaining parts of the peripheral surface of the tag  4600 . The second housing member  4604  may be removable from the first housing member  4602  and may define a battery cavity. In some cases, more or fewer housing members may be used. For example, multiple separate housing members may be used instead of the unitary first housing member  4602 . 
       FIG.  46 B  shows the tag  4600  with the second housing member  4604  detached from the first housing member  4602 . The second housing member  4604  may define a battery cavity  4610  for receiving the battery  4612 . The tag  4600  may also include a battery cover  4614  that may be removably coupled to the second housing member  4604 . The battery cover  4614  may be retained to the second housing member  4604  via clips, threads, or any other suitable features. The battery cover  4614  may help prevent accidental release of the battery  4612 . 
     The second housing member  4604  may be releasably retained to the first housing member  4602  (or any other suitable component of the tag  4600 ) via clips, latches, detents, channels, recesses, or any other suitable retention feature that retains the second housing member  4604  to the tag  4600 ) while allowing it to be detached if a user applies a sufficient force to overcome the retention force provided by the features. In other respects, such as the component set and the function and arrangement of such components (including circuit boards, audio systems, antennas, etc.), the tag  4600  may be substantially similar to other tags described herein. 
       FIGS.  47 A- 47 C  illustrate another example wirelessly locatable tag  4700  that has a generally lozenge-shaped form factor. The tag  4700  includes a body portion  4702  and a battery holder  4704 . The battery holder  4704  may be movable relative to the body portion  4702  to reveal a battery cavity.  FIG.  47 B  illustrates the tag  4700  with the battery holder  4704  extended, revealing the battery cavity  4710  so that a battery  4712  may be replaced. 
     The body portion  4702  may include a first housing member  4705 , which may define part of a bottom surface and some or all of the peripheral surface of the tag  4700 , and a second housing member  4703 , which may define part of a top surface of the tag  4700 . The battery holder  4704  may also define part of the top surface and part of the bottom surface of the tag  4700 . More particularly, the top and bottom surfaces of the battery holder  4704  may define part of the exterior top and bottom surfaces of the tag  4700  itself. In this way, the battery holder  4704  may be manipulated by a user via direct contact with the surfaces of the battery holder  4704 . 
     The battery holder  4704  may be opened by manipulating the battery holder in a manner similar to that described with respect to the tag  3500  ( FIGS.  35 A-B ). For example, while the user holds the body portion  4702 , the user may apply a twisting or rotational motion to the battery holder  4704  (as indicated by arrow  4701 ). This manipulation causes the battery holder  4704  to raise up relative to the body portion  4702 , thereby exposing the battery cavity  4710 . 
       FIG.  47 C  illustrates a partial exploded view of the tag  4700 . The first housing member  4705  defines a first cavity  4707  and a second cavity  4717 . The first cavity  4707  may contain device components such as circuit boards, audio systems, antennas, antenna assemblies, processors, and the like. As noted for other tags, the function and arrangement of such components (including circuit boards, audio systems, antennas, etc.) may be substantially similar to other tags described herein. The second housing member  4703  is coupled to the first housing member  4705  to define the exterior surfaces of the body portion  4702  and to at least partially enclose the first cavity  4707 . (Other configurations of housing members may be used instead of the first and second housing members, such as more or fewer housing members.) The battery holder  4704  is positioned in the second cavity  4717 . 
     The first housing member  4705  may define a first opening  4711  and the second housing member  4703  may define a second opening  4709 . The battery holder  4704  may be accessible through the first and second openings  4711 ,  4709 . More particularly, the exterior surfaces of the battery holder  4704  may be within the first and second openings  4711 ,  4709  such that a user can pinch the surfaces of the battery holder  4704  to apply the necessary manipulation to extend or retract the battery holder  4704 . 
     The battery holder  4704  and the body portion  4702  may include features that engage one another to cause the battery holder  4704  to extend upwards when twisted relative to the body portion  4702 . For example, in the example implementation shown in  FIG.  47 C , the battery holder  4704  defines guide pins  4714 , and the first housing member  4705  defines guide slots  4716  that engage the guide pins  4714 . The guide slots  4716  are angled so that a twisting motion applied to the battery holder  4704  will extend or retract the battery holder  4704  as the guide pins  4714  slide along the guide slots  4716 . 
     The tag  4700  may include seals to prevent ingress of liquid, dust, or other contaminants into the tag  4700  when the battery holder  4704  is in the retracted configuration.  FIGS.  48 A- 48 B  are partial cross-sectional views of the tag  4700 , viewed along line  48 A- 48 A in  FIG.  47 A , showing the battery holder  4704  in a retracted state ( FIG.  48 A ) and in an extended state ( FIG.  48 B ).  FIG.  48 A  shows example configurations for sealing the interface between the battery holder  4704  and the body portion  4702  of the tag  4700 . 
     With reference to  FIG.  48 A , the interfaces between the battery holder  4704  and the first housing member  4705  (at the first opening  4711 ) and between the battery holder  4704  and the second housing member  4703  (at the second opening  4709 ) may be sealed using compliant seals. In the example shown, a first sealing member  4814  may be attached to a first interface surface  4816  of the battery holder  4704 . In the retracted configuration, the first sealing member  4814  may contact a first sealing surface  4812  of the first housing member  4705 . Similarly, a second sealing member  4808  may be attached to a second interface surface  4806  of the battery holder  4704 . In the retracted configuration, the second sealing member  4808  may contact a second sealing surface  4810  of the second housing member  4703  (which may be a surface of a ledge defined along the wall of the second opening  4709 ). When the battery holder  4704  is in the retracted position, the first and second sealing members  4808 ,  4814  may be forced against their respective sealing surfaces, thereby inhibiting ingress of liquids, dust, or other contaminants. 
     The first and second sealing members  4808 ,  4814  may be formed of any suitable material, such as a compliant polymer material (e.g., an elastomer, silicone, or the like). They may be attached to their respective interface surfaces via adhesive or any other suitable attachment technique (e.g., co-molding, mechanical interlocking, etc.). While the first and second sealing members  4808 ,  4814  are shown attached to the battery holder  4704 , they may instead be attached to the sealing surfaces of the housing members. Further, other configurations of interface surfaces, sealing surfaces, and sealing members are also contemplated. 
     In some cases, the guide slots  4716  may include bumps, catches, protrusions, or other features that provide a tactile indication that the battery holder  4704  is fully extended or fully retracted. Such features may also help retain the battery holder  4704  in the fully extended or retracted positions. In some cases, when the battery holder  4704  is in a fully retracted position (and retained in said position via the bumps, catches, protrusions, or other features), the sealing members may be compressed between their respective sealing and interface surfaces, thereby forming a positive seal against contaminants. 
       FIGS.  49 A- 49 B  illustrate another example wirelessly locatable tag  4900 . The tag  4900  has a generally circular, puck-shaped form factor, similar to other tags described herein. The tag  4900  may include a first housing member  4902  and a second housing member  4904  that define substantially all of the exterior surfaces of the tag  4900 . For example, the first housing member  4902  may define all of a top surface and a portion (e.g., approximately half) of a peripheral side surface of the tag  4900 , while the second housing member  4904  may define all of a bottom surface and a portion (e.g., approximately half) of the peripheral side surface of the tag  4900 . From the outside, the first and second housing members  4902 ,  4904  may appear substantially identical to one another, thereby defining a substantially symmetrical shape. 
       FIG.  49 B  is a partial exploded view of the tag  4900 , showing the first and second housing members  4902 ,  4904  detached from one another. The tag  4900  may also include a sealing member  4906  configured to contact the first and second housing members  4902 ,  4904  to inhibit ingress of liquids or other contaminants. 
     The tag  4900  may include device components  4908 . The device components  4908  may include frames (e.g., frame members, antenna assemblies) circuit boards, circuit elements, processors, memory, sensors, radio circuitry (including antennas) for various wireless communications (e.g., UWB, WiFi, Bluetooth, etc.), or the like. Indeed, the device components  4908  may include any of the components that are used to provide the functions of a wireless tag as described herein. The tag  4900  may also include a battery  4912  to provide power for the electronic components. 
     The first and second housing members  4902 ,  4904  may be attached together via interlocking features defined by the first and second housing members  4902 ,  4904 . For example, as shown in  FIG.  49 B , the first housing member  4902  may define openings  4909  (or recesses or other suitable features) on a flange that mates with the second housing member  4904 . Correspondingly, the second housing member  4904  defines clips  4905  that engage the openings  4909  to retain the first and second housing members  4902 ,  4904  together. The first and second housing members  4902 ,  4904  may be separable by a user by prying or otherwise pulling the first and second housing members  4902 ,  4904  apart (e.g., with a fingernail or other tool or implement). 
     The openings and clips may be unitary with the first and second housing members (e.g., formed as a single piece), or they may be separate components that are attached to the first and second housing members. For example, rings that define the openings and clips may be attached to the first and second housing members. Where separate components are attached together, the components may be formed of a different material than the housing members. For example, where the housing members are polymer, rings (or other components) defining the openings and clips may be formed from metal, a different polymer material, or the like. In some cases, the openings and clips may be distributed on the housing members differently. For example, each housing member may define some openings and some clips. Retention features other than clips and openings may be used instead of or in addition to openings and clips. 
       FIGS.  50 A- 50 B  illustrate another example wirelessly locatable tag  5000 . The tag  5000  has a generally circular, puck-shaped form factor, similar to other tags described herein. The tag  5000  may include a body portion  5002  and a battery tray  5004  that define substantially all of the exterior surfaces of the tag  5000 . For example, the body portion  5002  may define all of a top surface, all of a bottom surface, and a portion of a peripheral side surface of the tag  5000 , while the battery tray  5004  may define a remaining portion of the peripheral side surface of the tag  5000 . The battery tray  5004  may be openable relative to the body portion  5002  to expose a battery cavity and facilitate battery replacement. The battery tray  5004  and the body portion  5002  may include complementary slots, slides, channels, rails, or other features that engage one another to guide the battery tray  5004  along a linear path into the body portion  5002 . The battery tray  5004  may be fully separable from the body portion  5002 , or it may be captive to the body portion  5002  so that it remains attached to the body portion  5002  even when in an open or extended position. The battery tray  5004  may be opened by a user pulling outwardly on the battery tray  5004  while holding the body portion  5002 . 
       FIG.  50 B  is a partial exploded view of the tag  5000 , showing the battery tray  5004  removed from the body portion  5002 . The battery tray  5004  may define a battery cavity  5010  for receiving a battery  5012  therein. The body portion  5002  may include a first housing member  5006  and a second housing member  5008 , which together may define an opening  5009  that receives the battery tray  5004 . 
     The tag  5000  may include device components  5016 . The device components  5016  may include frames (e.g., frame members, antenna assemblies) circuit boards, circuit elements, processors, memory, sensors, radio circuitry (including antennas) for various wireless communications (e.g., UWB, WiFi, Bluetooth, etc.), or the like. Indeed, the device components  5016  may include any of the components that are used to provide the functions of a wireless tag as described herein. The tag  5000  may also include an audio system  5014 , which may be any of the audio systems described herein (including, for example, an audio system that uses a portion of the second housing member  5008  as the diaphragm for producing audible output). 
       FIGS.  51 A- 51 C  illustrate another example wirelessly locatable tag  5100 . The tag  5100  has a generally circular, puck-shaped form factor, similar to other tags described herein. Whereas other puck-shaped tags may stack the audio system, circuit board and battery along a central (e.g., axial) axis of the puck, the audio system of the tag  5100  is positioned next to (e.g., in a generally planar arrangement with) other device components. 
     The tag  5100  may include a top housing member  5102 , which may define a top surface and a peripheral side surface of the tag  5100 , and a bottom housing member (or battery door)  5104 . The bottom housing member  5104  may be removably coupled to the top housing member  5102 , or another component of the tag  5100 , using any of the attachment techniques described herein, such as those described with respect to  FIGS.  12 A- 12 C and  14 A- 25 C . 
     As described herein, the tag  5100  may include any suitable type of audio system. As shown, the tag  5100  includes an audio system, within the housing, that includes a speaker that produces audio outputs. Sound from the speaker exits the tag  5100  through speaker openings  5106  that extend through the top housing member  5102 . 
       FIG.  51 B  shows the tag  5100  with the bottom housing member  5104  removed from the top housing member  5102 , with the battery  5112  removed. The bottom housing member  5104  may include latch members  5108  that engage complementary features on the tag  5100 . The bottom housing member  5104  may also include a compliant member that biases the battery  5112  into the tag  5100  and into engagement with battery connectors, as described above. 
       FIG.  51 C  is a partial exploded view of the tag  5100 . The tag  5100  may include a cover  5120  and a peripheral member  5122  to which the cover  5120  is attached. The cover  5120  and the peripheral member  5122  may define some or all of the top housing member  5102 . The cover  5120  may define the speaker openings  5106  of the top housing member  5102 . 
     The tag  5100  also includes an audio system  5124 , which may be positioned below the speaker openings  5106  and may include a speaker as described above. In some cases, the audio system  5124  includes a coil and magnet to move the top housing member as a diaphragm, similar to the other audio systems described herein. 
     The tag  5100  also includes a circuit board  5126 . The circuit board  5126  may include device components such as circuit elements, processors, memory, sensors, radio circuitry (including antennas) for various wireless communications (e.g., UWB, WiFi, Bluetooth, etc.), or the like. The circuit board  5126  may have a shape that conforms to or otherwise allows the circuit board to be positioned next to the audio system  5124 . For example, the circuit board  5126  may define a clearance area  5125 , and the audio system  5124  may be nested or otherwise positioned in the clearance area  5125 . 
     The tag  5100  may also include a frame member  5128 . The frame member  5128  may define a battery cavity  5129  that receives the battery  5112 . The frame member  5128  may also support other components of the tag  5100 . For example, the circuit board  5126 , antennas, and the audio system  5124  may be attached to the frame member  5128 . Further, the top and bottom housing members  5102 ,  5104  may be attached to the frame member  5128 . The frame member  5128  may perform some or all of the functions of the frame member  512  and/or antenna assembly  508  of the tag  500  (described above). 
     As shown in  FIG.  51 C , the audio system  5124 , battery  5112 , and circuit board  5126  are all positioned roughly in the same lateral plane. Stated another way, at least some portion of each component may lie in a single plane that is generally parallel to the top surface of the cover  5120 . This configuration may produce a tag with a larger diameter, but a smaller axial height, than tags in which the audio system, battery, and circuit board are stacked along the axis (e.g., as shown in  FIG.  5 B ). 
       FIGS.  52 A- 52 C  depict an additional example embodiment of a wirelessly locatable tag  5200 , showing another form factor for the tag.  FIG.  52 A  illustrates a perspective view of the tag  5200 , which has a generally cylindrical shape. The tag  5200  includes a body portion  5202  and a battery cover  5204  that may be removably coupled to the body portion  5202 . The body portion  5202  may house device components, such as circuit boards, audio systems, antennas, antenna assemblies, processors, and the like. As noted for other tags, the function and arrangement of such components (including circuit boards, audio systems, antennas, etc.) may be substantially similar to other tags described herein. The tag  5200  may include an audio system that includes a speaker that produces audio outputs. Sound from the speaker exits the tag  5200  through speaker openings  5206  in the body portion  5202 . 
       FIG.  52 B  depicts an exploded view of the tag  5200 , illustrating various combinations of batteries and battery covers that may be used with the body portion  5202 . These components may be interchangeable, allowing a user to select aspects of the tag&#39;s appearance and function. 
     As shown in  FIG.  52 B , a single battery  5212  may be used with the battery cover  5204 , corresponding to the overall appearance of  FIG.  52 A . In another application, a larger battery cover  5214  may be used, along with two batteries  5212 , thus providing increased battery life for the tag  5200 . In another application, a battery cover  5216  may include an attachment feature  5217 , shown in  FIG.  52 B  as a loop. The attachment feature  5217  may be used to attach the tag  5200  to other objects, such as a key ring or split ring, lanyard, clip, strap, or the like. In another application, a battery cover  5218  may include a charging port  5220  and may be configured for use with a rechargeable battery  5222 . The battery cover  5218  may optionally include charging and/or other battery control circuitry so that the user can choose to use either rechargeable or non-rechargeable batteries with the same body portion  5202 . 
       FIG.  52 C  illustrates a partial cross-sectional view of the tag  5200 , viewed along line  52 C- 52 C in  FIG.  52 A . The tag  5200  may include a frame member  5230  in the body portion  5202 . The frame member  5230  may serve as a mounting structure for other components of the tag  5200 , such as a circuit board  5226 , an audio system  5224  (which may include a speaker and which directs sound out of the speaker openings  5206 ), or the like. In some cases, one or more antennas are mounted to the frame member  5230  in a manner similar to the antenna assembly  508  described above. The circuit board  5226  may include a substrate and may include processors, memory, and other circuit elements that generally perform the electrical and/or computational functions of the tag  5200 . The circuit board  5226  may also include conductors and/or electrical interconnects that electrically couple the various electrical components of the tag  5200 . The circuit board  5226  may also include or be coupled to the battery  5212 . 
     The battery cover  5204  may be releasably retained to the main body  5202  in any suitable way. For example, the battery cover  5204  may thread onto the main body  5202 , or it may be retained using friction and/or an interference fit. The battery cover  5204  and/or the body  5202  may include locking or latching mechanisms to inhibit accidental removal of the battery cover  5204 . More particularly, the battery cover  5204  may include latches, catches, or other features that must be released or disengaged (e.g., by squeezing, applying a tool, or the like) before the battery cover  5204  can be removed by pulling or twisting. The tag  5200  may include a sealing member  5228  configured to inhibit ingress of liquid, dust, or other contaminants into the tag  5200 . 
     In some cases, the tag  5200  may have the same or substantially the same overall size and shape as a battery, such as an “AA” or “AAA” size battery (or any other size or form factor of battery). In such cases, the tag  5200  may be used in place of a conventional battery to allow convenient location tracking of many different battery-operated devices. Accordingly, a device like a remote control, flashlight, camera, or the like, may be made wirelessly locatable without having to attach an external component, modify the device, or otherwise change the functionality or usability of the device. 
     Where the tag  5200  is configured to replace a battery, the tag  5200  (or a different but similarly shaped tag) may define a positive terminal and a negative terminal on exterior locations that correspond to the locations of positive and negative terminals of an “AA” or other sized battery (e.g., at locations  5203 ,  5205  in  FIG.  52 A ). The tag  5200  may be configured to pass current from the negative terminal  5205  to the positive terminal  5203  of the tag  5200  such that the tag  5200  does not disrupt the power circuit of the device and allows the device to operate normally (using the power provided from other batteries of the device), albeit with reduced battery capacity. In some cases the battery  5212  of the tag  5200  may provide power to the components of the tag  5200 , while also providing power through the external terminals  5203 ,  5205  of the tag  5200 , thereby allowing the tag  5200  to provide power to the device in which it is installed, while also providing wireless tracking functionality for the device. 
       FIGS.  53 A- 53 C  illustrate another example wirelessly locatable tag  5300  having another form factor. In particular, the tag  5300  has a generally flat, rectangular-prism shaped exterior housing. The tag  5300  includes a first housing member  5302  that defines all or substantially all of a top surface and part of the peripheral surface of the tag  5300 . The tag  5300  also includes a second housing member  5304  that defines part of (e.g., approximately half of) a bottom surface of the tag  5300  and part of the peripheral surface of the tag  5300 . The second housing member  5304  may not be intended to be removed by a user of the tag  5300 . The tag  5300  may also include a third housing member  5306 , which may also define part of (e.g., approximately half of) the bottom surface of the tag  5300  and part of the peripheral surface of the tag  5300 . 
       FIG.  53 B  shows a partial cross-sectional view of the tag  5300 , viewed along line  53 B- 53 B in  FIG.  53 A , showing an example arrangement of components within the tag  5300 . The tag  5300  may include a battery  5312 , an audio system  5314 , and device components  5310 . The device components  5310  may include circuit boards, circuit elements, processors, memory, sensors, radio circuitry (including antennas) for various wireless communications (e.g., UWB, WiFi, Bluetooth, etc.), or the like. Indeed, the device components  5310  may include any of the components that are used to provide the functions of a wireless tag as described herein. The audio system  5314  may operate similar to other audio systems described herein. For example, a coil may be attached to an interior surface of the first housing member  5302 , and a magnet may provide a magnetic field to allow the coil to operate as a speaker. By passing a signal (e.g., current) through the coil, a portion of the first housing member  5302  can move in a manner similar to a speaker diaphragm. Further, the audio system may be used to produce tactile outputs that a user can feel when touching the first housing member  5302 . Of course, other types of audio systems and/or tactile output generators may be used instead of or in addition to the audio system  5314 . 
     The third housing member  5306  may be removable to provide access to a battery cavity.  FIG.  53 C  illustrates a partial cross-sectional view of the tag  5300  with the third housing member  5306  removed from the rest of the tag  5300 . The third housing member  5306  may define at least part of a battery cavity for a battery  5312 . Features of the third housing member  5306  may engage corresponding features of the first and/or second housing members  5302 ,  5304 , or any other component of the tag  5300  (e.g., a frame member), to retain the third housing member  5306  to the tag  5300  while also allowing it to be removed for battery replacement. Such features may include clips, latches, detents, or the like. The third housing member  5306  may be removed from the tag  5300  by prying with a fingernail, tool, or other implement inserted in a gap between the third housing member  5306  and another part of the tag  5300 . 
     In other respects, such as the component set and the function and arrangement of such components (including circuit boards, audio systems, antennas, etc.), the tag  5300  may be substantially similar to other tags described herein, and the tag  5300  may include any of the components and/or provide any of the features of any tag described herein. 
       FIGS.  54 A- 54 B  illustrate another example wirelessly locatable tag  5400  having a generally flat, rectangular-prism shaped exterior housing. The tag  5400  includes a first housing member  5402  and a second housing member  5404 , which may be removably coupled to the first housing member  5402 . 
     The tag  5400  is similar to the tag  5300 , but has a different arrangement of components within the housing.  FIG.  54 B  illustrates the tag  5400  with the first housing member  5402  detached from the second housing member  5404 . The tag  5400  includes two batteries  5412 , an audio system  5414 , and device components  5410 . The device components  5410  and audio system  5414  may be the same as or similar to the corresponding components in the tag  5300 , and for brevity their details may not be repeated here. Due to the extra battery, the tag  5400  may have increased battery life as compared to single-battery tags. 
       FIGS.  55 A- 55 B  illustrate another example wirelessly locatable tag  5500  having a generally flat, rectangular-prism shaped exterior housing. The tag  5500  includes a first housing member  5502  and a second housing member  5504 , which may be removably coupled to the first housing member  5502 . The tag  5500  may be configured to use a conventional speaker or other audio-producing component, and may therefore include speaker openings  5506  that extend through the first housing member  5502 . 
       FIG.  55 B  is a partial cross-sectional view of the tag  5500 , viewed along line  55 B- 55 B in  FIG.  55 A . The tag  5500  includes a battery  5512  and device components  5510 , which may be the same as or similar to the corresponding components in other tags described herein, and for brevity their details may not be repeated here. The tag  5500  also includes a speaker  5508  (or other suitable audio-producing component) that produces audio outputs, which in turn pass through the speaker openings  5506  to be perceived by a user. 
     As described elsewhere herein, the functionality of a wirelessly locatable tag may be incorporated into other types of devices and/or integrated with other components, accessories, features, or the like. In one such example, as shown in  FIGS.  56 A- 56 B , a wirelessly locatable tag may be incorporated into a device that includes a built-in attachment cord or strap. 
     The tag  5600  may include a body portion  5602  and a cord portion  5604 . The body portion  5602  may include some or all of the components that provide the functionality of a wirelessly locatable tag, such as circuit boards, circuit elements, processors, memory, sensors, radio circuitry (including antennas) for various wireless communications (e.g., UWB, WiFi, Bluetooth, etc.), or any other components that are used to provide the functions of a wireless tag as described herein. The cord portion  5604  may be a flexible rope, cable, or other member that can be attached to another object. In some cases, electronic components of the tag  5600  are housed in or incorporated in the cord portion  5604 . For example, an antenna (e.g., a flexible conductor such as a wire or metallized thread) may be incorporated in the cord portion  5605 . Flexible conductors incorporated into a cord portion may be used for other operations or features as well, such as carrying signals, detecting contact with other objects or people, or the like. 
     The body portion  5602  may define a first portion  5606  and a second portion  5608 , which can be separate from one another to allow the loop to be opened and the tag  5600  to be attached to another object.  FIG.  56 B  shows the tag  5600  in an open configuration, in which the first portion  5606  is separated from the second portion  5608 . The first and/or second portions  5606 ,  5608  may include retention features  5616  that releasably retain the first and second portions together. The retention features  5616  may include, for example, clips, latches, magnets, or the like. The body portion  5602  may be separable by simply pulling the first and second portions  5606 ,  5608  apart, though in other cases a user must perform other manipulations, such as unlocking or unlatching a retention feature, twisting, prying, using a tool, or the like. 
     The tag  5600  may include sensors or other systems that detect whether the tag  5600  is in an open ( FIG.  56 B ) or closed ( FIG.  56 A ) configuration. Such sensors may include for example Hall effect sensors, accelerometers (which detect a characteristic motion caused by the tag being opened or closed), microphones (which detect a characteristic sound caused by the tag being opened or closed), optical sensors, or the like. The tag  5600  may perform different actions based on whether the tag  5600  is open or closed. For example, the tag  5600  may power down or transition to a low-power mode (e.g., deactivating one or more systems or processes) when the tag  5600  is open, and power up or transition to a normal operating mode when the tag  5600  is closed. As another example, upon detecting that the tag  5600  has been opened or closed, the tag  5600  may send, via a cloud-based service, a message indicating the change in the tag&#39;s status. An owner or other authorized individual may receive a message from the cloud-based service that provides information about the tag, such as its location, when it was opened, where it was when it was opened, the time when it was opened, or the like. 
     The tag  5600  may include input and/or output components accessible on the outside of the tag  5600 . For example, the tag  5600  includes optional buttons  5612  with which a user may interact to control aspects of the tag  5600 . For example, the buttons  5612  may control operations such as turning the tag  5600  on or off, causing the tag to enter a pairing mode, causing the tag to send a “lost” message, or the like. The buttons  5612  may include moving parts and mechanical actuating components (e.g., dome switches). In some cases, the buttons  5612  may be defined by touch-sensitive input regions (e.g., capacitive touch-sensing regions). 
     The tag  5600  may also include output components, such as a display  5614 , which may include or use any suitable display technology such as LED, LCD, OLED, E ink, or the like. The display  5614  may display various types of information. For example, the display  5614  may display status information about the tag  5600 , including battery charge level, an owner&#39;s name, the status of the tag (e.g., if it has been reported lost), or the like. In some cases, the display  5614  may display different information if the tag is reported lost. For example, upon receiving an indication that the tag has been reported to be lost, the display  5614  may begin displaying a message indicating that it has been reported lost and providing instructions on how the user wants the lost item to be handled (e.g., do not move from this location, return to owner, call owner, etc.). 
     The tag  5600  may also include indicator lights  5610 . The indicator lights  5610  may be LEDs or any other suitable light sources. The indicator lights  5610  may indicate a status of the device, such as a power state, battery charge level, operating mode, lost/not lost status, or the like. In some cases, the indicator lights  5610  may be activated in response to the tag  5600  being reported lost. For example, the indicator lights may flash (or remain steadily illuminated) to alert nearby people to the presence of the tag and its status as being lost. The indicator lights  5610  may be used for other purposes as well. 
       FIG.  57    depicts another example tag  5700  having a similar configuration as the tag  5600  but having a different approach to opening and closing the loop of the cord. In particular, the tag  5700  includes a body portion  5702 , which may be the same as or substantially similar to the body portion  5602 , except that the body portion  5702  may not be separable. Instead, the cord portion  5704  is removably coupled to the body portion  5702  at least at one end of the cord portion  5704 , thereby allowing the tag  5700  to be attached to other objects by forming a loop with the cord portion  5704 . The cord portion  5704  may include a connector  5708  that mates with a connector  5706  of the body portion  5702 . The connectors  5708 ,  5706  may include retention features such as clips, latches, magnets, or the like. The tag  5700  may detect whether the cord portion  5704  is attached to or detached from the body portion  5702 , and cause the tag  5700  to operate in a certain way based on the determination, as described above. The tag  5700  may include sensors to determine when the cord portion is attached or detached. Such sensors may include for example Hall effect sensors, accelerometers (which detect a characteristic motion caused by the cord portion being attached or detached), microphones (which detect a characteristic sound caused by the cord portion being attached or detached), optical sensors, or the like. 
       FIGS.  58 A- 58 C  illustrate another example wirelessly locatable tag  5800 , showing yet another form factor for a tag that provides some or all of the tag functionality described herein. In particular, the tag  5800  has a generally rectangular shape with a small thickness dimension, allowing the tag  5800  to fit into small places like a credit card slot in a wallet, or a side pocket of a purse, or the like. In some cases, the tag  5800  has a thickness dimension (e.g., the height of the tag  5800  as viewed in  FIG.  58 B ) that is less than about 5.0 mm, about 4.0 mm, about 3.0 mm, about 2.0 mm, or about 1.0 mm. 
       FIG.  58 A  shows a top view of the tag  5800 . Some internal components of the tag  5800  are shown in phantom lines. For example, the tag  5800  may include a battery  5812 , a wireless charging coil  5810 , and device components  5814 . The device components  5814  may include some or all of the components that provide the functionality of a wirelessly locatable tag, such as circuit boards, circuit elements, processors, memory, sensors, radio circuitry (including antennas) for various wireless communications (e.g., UWB, WiFi, Bluetooth, etc.), or any other components that are used to provide the functions of a wireless tag as described herein. 
       FIG.  58 B  shows a partial cross-sectional view of the tag  5800 , viewed along line  58 B- 58 B in  FIG.  58 A .  FIG.  58 B  shows an example arrangement of the components of the tag  5800 . The tag  5800  may include a housing  5801  ( FIG.  58 A ) that defines the exterior surfaces of the tag  5800  and defines an internal volume of the tag. The housing  5801  may include a bottom housing member  5802 , which may define the bottom surface and some or all of the peripheral side surface of the tag  5800 , and a top housing member  5804 , which may define the top surface of the tag  5800 . Other configurations of housing members are also contemplated. 
     The battery  5812  may be stacked above the wireless charging coil  5810 . The battery  5812  may be charged by placing the tag  5800  on a suitable wireless charger, which may have a transmitting coil configured to inductively couple to the charging coil  5810  and provide wireless power to the coil  5810  that is then used to charge the battery. The device components  5814  may include control circuits that control the power being provided to the battery  5812  from the charging coil  5810 . 
       FIG.  58 C  illustrates another example wirelessly locatable tag  5820 . The tag  5820  may be substantially identical to the tag  5800 , except that instead of a wireless charging coil  5810 , the tag  5820  includes charging contacts  5830  that provide power to the battery  5832  and/or other electronic components of the tag  5820 . The charging contacts  5830  may include exposed electrically conductive members (e.g., copper pads) that are exposed along or otherwise define part of the bottom exterior surface of the tag  5820 . The tag  5820  may be charged by placing the charging contacts  5830  in contact with corresponding contacts of a battery charger. 
     The tag  5820  may also include first and second housing members  5824 ,  5822 , and device components  5834 , each of which may be the same as or similar to the corresponding components of the tag  5800 . Further, the tags  5800 ,  5820  may include audio systems to provide audible and/or tactile outputs. The audio systems may include piezoelectric elements or other materials or components that can be implemented in a low-profile housing such as that shown in  FIGS.  58 A- 58 C . 
     The housing members of the various tags described herein (e.g., the components of the tags that define the exterior surfaces of the tags and/or the body portions of the tags) may be formed from any suitable material. For example, the housing members may be formed from or include polymers, metals, composites (e.g., fiber-reinforced polymers), or the like. Similarly, any of the frames, frame members, antenna assemblies, of the tags described herein may be formed from materials such as polymers, composites (e.g., fiber-reinforced polymers), or the like. Tag components such as frames, housing members, circuit boards, or the like, may be coupled to one another in various ways, including but not limited to ultrasonic welds, adhesives, heat stakes, rivets, mechanically interlocked features, laser welds, melt bonds, or the like. 
     While the various example tags described herein may focus on a particular set of components and features, the tags may include or provide more, fewer, or different components and features. For example, tags as described herein may include displays that can provide graphical outputs including text, images, or the like. Such displays may be incorporated in the tags so that they can be seen by a user. The displays may include any suitable display technology, including LED, LCD, OLED, E ink, or the like. Displays may also incorporate touch and/or force sensing systems that detect touch- and or force-based inputs applied to the display. Inputs applied to a touch- and/or force-sensitive display may control operational aspects of a tag, such as by changing operating modes, changing settings, inputting data, and the like. Tags may also include other visual output systems, such as indicator lights, which also provide visual output to a user (e.g., indicating an operating mode of the tag, a power state, whether the tag has been reported as lost, etc.). 
     As noted above, various different types of audio systems are contemplated for use with the wirelessly locatable tags described herein. For example, one type of audio system may use a wall of a housing member that defines an exterior surface of the tag as a sound-producing element or diaphragm. Another type of audio system may include a speaker that produces sound which then passes through openings in the housing. Yet another type of audio system is a piezoelectric element that can either move a portion of a housing member (as a diaphragm) or move a separate diaphragm or member to produce sound. It will be understood that tags that are described as using one type of audio system may additionally or instead use another type of audio system. 
     In order to begin using the tags described herein, an initialization or pairing process may be performed, in which the tag communicates with another device, such as a smartphone, laptop, desktop, or tablet computer, or the like. The initialization process may be used to associate a particular tag with a particular user or user account in the device-location relay network. The initialization process may also be used to establish a trusted communication link between the tag and a particular device. This trusted communication link may allow the device to interact with the tag in ways that are not accessible to other (e.g., untrusted) devices. For example, a tag that has been paired with a user&#39;s smartphone may allow that smartphone to control the operation of the tag, change its mode of operation, or the like, while other devices (e.g., devices with which the tag has not been paired) may be unable to perform these actions. 
     In some cases, an initialization mode may be entered by providing an input to a tag. For example, a tag may include a button, switch, or other input mechanism that a user can manipulate (e.g., push) to cause the tag to enter an initialization mode. When the input is detected by the tag, the tag may enter the initialization mode in which the tag may perform certain actions. For example, as described above, the tag may begin sending a beacon signal or change (e.g., increase) the frequency at which it is sending a beacon signal. The beacon signal may be a wireless communication via a Bluetooth protocol, a UWB protocol, or the like, and may be detectable by another device such as a smartphone or computer. Once an initialization process is complete, the tag may enter a “normal” operating mode, which may include changing (e.g., decreasing) the frequency of its beacon signal. 
     In some cases, tags may not have input devices, or they may be configured so that its input devices do not function to activate an initialization mode. In such cases, other techniques may be used to cause the device to enter an initialization mode. For example, a tag may be configured to enter an initialization mode in response to the onset of power being provided to the tag from a battery or other power source. In such cases, upon power being provided to the tag, the tag may activate an initialization mode for a duration, such as one minute, five minutes, or any other suitable duration. After this duration expires, the user can reactivate the initialization mode, if required, by removing and reinserting the battery (or otherwise interrupting the power supply to the tag). Where tags are provided or sold with the batteries in place, such as in one of the battery cavities of the tags described above, the tag may include an insulating material between the battery and a contact of a battery connector. Upon removal of the insulating material (which a user may simply pull out of the tag using a provided pull-tab or handle), power is supplied to the tag and the initialization mode is activated. 
     Other techniques for causing tags to activate an initialization mode are also contemplated. For example, a tag may include a battery door that can be moved between two positions. In a first position, the battery door may be securely retained to the tag but configured so that power does not flow from the battery to the tag&#39;s circuitry, and in a second position, the battery door may also be securely retained to the tag but configured so that power does flow to the tag&#39;s circuitry. The user can simply move the battery door from the first position to the second position, which will cause power to be provided to the tag&#39;s circuitry and thus activate the initialization mode. The flow of power from the battery may be interrupted by an internal switching mechanism, by physically separating the battery from a battery contact, or any other suitable technique. In some cases, the tag may include a sensor to determine the position of the battery door. For example, the tag may include a Hall effect sensor, optical sensor, capacitive sensor, or the like. Upon sensing that the battery door has been moved to the second position, the tag may activate the initialization mode. 
     As yet another example, a tag may be provided with a battery tray or door partially or fully detached from the rest of the tag. Attaching or inserting the battery tray or door may cause the tag to begin receiving power and thus enter the initialization mode. As another example, a tag may include an accelerometer, and upon detecting an acceleration or motion characteristic of a particular type of input (e.g., a tap, a particular pattern of taps, a shake, or the like), the tag may activate the initialization mode. As yet another example, if the tag includes an audio system that can be used to detect deformations of the housing (such as the audio systems described with respect to  FIG.  26 B ), the tag may activate the initialization mode in response to detecting a particular input via the audio system (e.g., a single press, a single press having a particular duration, a particular pattern of presses). 
     The tag may include sensors that determine when the tag has been removed from packaging, and activate an initialization mode upon detecting that it has been removed from the packaging. For example, the tag may include a light sensor that detects when it is removed from an opaque packaging. As another example, it may include an oxygen sensor that detects when it is removed from a sealed packaging. As yet another example, it may include a Hall effect sensor, capacitive sensor, magnetic sensor, or other suitable sensor that detects when a conductive or magnetic component of a packaging (e.g., a strip of metal attached to a box lid) is moved away from the tag. As yet another example, tag packaging may include a spring-loading mechanism that imparts a characteristic motion to the tag when the packaging is opened. An accelerometer in the tag may detect the characteristic motion and trigger the initialization mode upon detecting the motion. As yet another example, tag packaging may include or define a Faraday cage, and the tag may activate an initialization mode upon detecting wireless signals (which may occur once the tag is removed from the Faraday cage). 
     When initializing a tag, a smartphone (or other device such as a tablet computer) communicates with the tag, as described above. The tag may be configured to activate or trigger an initialization mode on the smartphone. For example, as described herein, wirelessly locatable tags may include NFC antennas. The smartphone may include an NFC reader that can detect when it is within a certain distance of the NFC antenna of the tag (e.g., three inches, or any other suitable distance), and in response to detecting that it is within that distance, trigger an initialization mode or initialization process. This may include launching an application on the smartphone or displaying graphical objects (e.g., a graphical user interface) that guides a user through the initialization process. 
     In some cases, the tag itself may detect when an NFC reader of another device communicates with the tag via NFC, and upon detecting a communication with the other device, the tag may activate its initialization mode. Thus, the initialization mode of the tag may be activated by the action of bringing the tag and other device into close proximity (e.g., within NFC communication range, such as about three inches or less). In such cases, prior to bringing a smartphone into NFC range of the tag, the user may activate an application or otherwise cause his or her smartphone to enter a mode in which the phone&#39;s NFC reader will communicate with the tag. In this manner, initialization of the tag may be simplified and streamlined, as the user can simply request the initialization mode on a phone, tap the phone on the tag, and the initialization process will begin. 
     Tags described herein use batteries to provide power to the electrical components. The batteries may be non-rechargeable batteries, which can be replaced when they are exhausted, or they may be rechargeable batteries, which can be recharged and reused multiple times. Battery replacement, either of rechargeable or non-rechargeable batteries, may be facilitated by the housing designs, described herein, that provide access to a battery cavity to allow the batteries to be removed by a user. In implementations where rechargeable batteries are used, tags may be provided with non-removable batteries, and the tags may include charging components that allow the batteries to be recharged while they remain housed in the tags. 
     Various types of charging components may be incorporated into wirelessly locatable tags to facilitate the charging of rechargeable batteries.  FIGS.  59 - 60    illustrate two example wirelessly locatable tags using different charging components.  FIG.  59    shows a wirelessly locatable tag  5900  that is configured for wireless charging. More particularly, the tag  5900  may be configured to be placed on or proximate to a wireless charger  5902 . The wireless charger  5902  may include an output coil that is configured to inductively couple to a charging coil in the tag  5900 . Via electromagnetic interaction with the output coil, the charging coil in the tag provides (wireless) power to battery charging circuitry in the tag  5900 , thereby charging the battery (and optionally providing power directly to circuitry of the tag  5900 ). In particular, the output coil may produce a magnetic field, which in turn induces a current in the charging coil of the tag, and the induced current may be used to recharge the tag&#39;s battery. The housings of the tag  5900  and the charger  5902  may be configured to limit or minimize shielding of or interference with the inductive coupling between the charging and the output coil. For example, the tag  5900  and the charger  5902  may be configured so that the portions of the housing that are between the output and charging coils are substantially nonconductive, such as a polymer material. 
     The charger  5902  and tag  5900  may also include an alignment system to help a user properly align the tag  5900  relative to the charger  5902  to facilitate wireless charging. Such alignment systems may include magnets, complementary protrusions/recesses (or other complementary physical features), visual alignment indicators, or the like. While the charger  5902  is shown as a circular puck-style charger, this is merely one example embodiment of an external charging device, and the concepts discussed herein may apply equally or by analogy to other external charging devices, including charging mats, docks, electronic devices with built-in wireless charging functionality (e.g., alarm clocks, another electronic device such as a mobile phone or tablet computer), differently shaped chargers, or the like. 
       FIG.  60    shows a wirelessly locatable tag  6000  with a charging port  6002  configured to receive power cable  6004 . The power cable  6004  supplies electrical power to the tag  6000 , which is used to charge the battery and optionally provide power to the tag  6000  while the battery is charging. In some cases, tags may include both a charging port and wireless charging systems, thereby allowing a user to use either wired or wireless charging. 
     In some cases, it may be desirable to operate a wirelessly locatable tag indefinitely, without having to replace or recharge a battery. This may be particularly useful in cases where tags are used in static installations to help users locate certain objects (e.g., fire extinguishers, defibrillators), to automatically trigger users&#39; devices to take certain actions (e.g., triggering a user interface object to appear on a user&#39;s phone when a user approaches a location such as a painting, retail display, or the like), or any other instance where tags are stationary and/or it is desired to provide continuous power or otherwise obviate the need to replace batteries (e.g., in a vehicle). To accommodate these and other use cases, mounting bases may be provided that attach to tags in place of the batteries (and optionally in place of a battery door). The mounting bases may securely support the tags and also provide electrical power to the tags instead of a battery. 
       FIGS.  61 A- 65 B  illustrate an example mounting base system that may be used to hold and provide power to wirelessly locatable tags.  FIG.  61 A  illustrates an example tag  6102 , which may be an embodiment of the tag  500 , described above. The tag  6102  is shown with a bottom housing member (or battery door)  6104  and battery removed. The bottom housing member  6104  includes latch members  6106  that engage corresponding features of the tag  6102  (e.g., channels or recesses) to releasably retain the bottom housing member  6104  to the tag  6102 . 
       FIG.  61 A  also shows a mounting base  6108  to which the tag  6102  may be coupled in place of the bottom housing member  6104  and the battery.  FIG.  61 B  shows the tag  6102  coupled to the mounting base  6108 . 
     The mounting base  6108  includes latch members  6110 , which may have a shape that is the same as or substantially similar to the latch members  6106  of the bottom housing member  6104 . For example, the latch members  6110  may be configured to engage the same features of the tag  6102  that the latch members  6106  engage to retain the bottom housing member  6104  to the tag  6102 . In this way, the tag  6102  may be attached to and detached from the mounting base  6108  in substantially the same manner as the bottom housing member  6104  and without requiring a different set of attachment features in the tag  6102  for each of the bottom housing member and the mounting base. 
     The mounting base  6108  may also include a contact block  6112  that is disposed in the battery cavity of the tag  6102  when the tag  6102  is attached to the mounting base  6108 . The contact block  6112  may have a shape that is the same as or similar to at least a portion of the battery that is designed to fit in the tag  6102 . In this way, the contact block  6112  may extend into the battery cavity of the tag  6102  and engage the battery connector of the tag  6102  in a manner that is the same as or similar to the type of battery that powers the tag  6102 . 
     The mounting base  6108  may include or be attached to a cable  6109 , which may provide power (e.g., an input current) to the tag  6102  through the mounting base  6108 , and more particularly, through conductive members that are integrated with the contact block and engage with the battery connector of the tag  6102 . The contact block  6112  may be formed of a polymer or other insulating or substantially non-conductive material. The non-conductive material allows the mounting base  6108  to support conductive members (described with respect to  FIG.  62   ) that provide electrical current to the tag  6102 , without shorting the conductive members together. 
       FIG.  62    shows additional details of the mounting base  6108 . The mounting base  6108  includes the contact block  6112 . The mounting base  6108  may also include first and second conductive members  6202 ,  6204 . The first conductive members  6202  may be positioned in a location that generally corresponds to the negative terminal of a button cell battery. Accordingly, due to the position of the first conductive members  6202 , when the tag  6102  is mounted on the mounting base  6108 , the first conductive members  6202  may conductively couple to the deflectable arm of the battery connector that is configured to contact the negative terminal of the button cell battery (e.g., the third deflectable arm  1008 ,  FIG.  10 B ). Similarly, the second conductive members  6204  may be positioned more towards the periphery of the contact block  6112 , at a location that generally corresponds to the positive terminal of the button cell battery. The second conductive members  6204  may thus conductively couple to the deflectable arms of the battery connector that is configured to contact the positive terminal of the button cell battery (e.g., the first and second deflectable arms  1004 ,  1006 ,  FIG.  10 B ). 
     The first and second conductive members  6202 ,  6204  may provide electrical power to the tag  6102  to power the tag in the absence of the battery. The power provided may mimic the power provided by a battery. For example, the mounting base  6108  may provide 1.5 volt direct current to the tag  6102  via the first and second conductive members  6202 ,  6204 . In some cases, the power delivered through the cable  6109  is 1.5 volt direct current, in which case the current may be provided directly from the cable  6109  to the first and second conductive members  6202 ,  6204 . More generally, the power delivered through the cable  6109  may be supplied from a DC power supply that provides the same or similar DC power that would otherwise be provided by the battery or batteries that power the tag. 
     In other cases, the cable  6109  delivers electrical power with different characteristics to the mounting base  6108  (e.g., 120 volt alternating current, 5 volts direct current, etc.). In such cases, the mounting base  6108  may include one or more power conversion systems to convert incoming power to a voltage or current suitable to operate the tag  6102  (e.g., an ac-to-dc converter). Such systems may include, for example, air core or magnetic core transformers, switched-mode power supplies (e.g., boost converters, buck converters, boost-buck converters, or other chopper circuits), analog voltage regulation circuits (e.g., voltage regulators, voltage reducers, clamp circuits, voltage divider circuits, voltage multiplier circuits, compensation networks, rectifier circuits, inverter circuits, and the like), or the like. The cable  6109  may be permanently attached to the mounting base  6108  (as shown), or it may be removable. For example, the mounting base  6108  may include a port for receiving the plug of a USB cable or other suitable power cable. 
     The power cable  6109  may be configured to plug into a power supply. For example, the power cable  6109  may be configured to plug into a residential AC power supply. In some cases, instead of or in addition to the power cable  6109 , a plug (e.g., a two- or three-prong plug) may be integrated with the mounting base. In such cases, when the mounting base  6108  is plugged into an outlet, the mounting base may be mechanically supported in place by the physical plug/outlet connection. 
     The first and second conductive members  6202 ,  6204  are arranged so that at least one of the first conductive members  6202  and at least one of the second conductive members  6204  contacts the battery connector of the tag  6102  regardless of the radial position of the tag  6102  relative to the mounting base  6108  when they are attached. In the example shown, the tag  6102  can be attached to the mounting base  6108  in three different orientations, due to the three latch members and three corresponding engagement features of the tag  6102 . The first and second conductive members  6202 ,  6204  are arranged in three pairs so that power is supplied to the battery connector regardless of which orientation the tag  6102  is in. Other configurations of first and second conductive members  6202 ,  6204  are also contemplated to ensure that power is provided regardless of tag orientation. Further, the orientation, position, shape, or other aspect of the first and second conductive members  6202 ,  6204  may be designed in conjunction with the particular battery connector configuration of the tag  6102 . Thus, while the arrangement of the first and second conductive members  6202 ,  6204  are configured to mate with the battery connector  900  ( FIG.  9   ), different arrangements may be used to mate with different battery connectors (e.g., those shown in  FIGS.  11 A- 11 D ). 
       FIG.  63    is an exploded view of the mounting base  6108 . The mounting base may include the contact block  6112  and its associated first and second conductive members  6202 ,  6204 . The mounting base  6108  may include a housing  6312  to which the other components of the mounting base  6108  may be coupled. The housing  6312  may define the latch members  6110  (e.g., the latch members  6110  and the housing  6312  may be a single unitary piece of material), or they may be separate members that are attached to the housing  6312 . 
     The housing  6312  may define an opening  6311  through which the end of the cable  6109  may extend. The cable  6109  may include a strain relief structure  6309  that helps prevent damage to the cable  6109  (and/or termination points of the wires inside the housing  6312 ) due to bending or twisting relative to the housing  6312 . The cable  6109  may include conductors  6310  that carry electrical power to the mounting base  6108  and that are terminated on a circuit board  6306 . Where the cable  6109  includes other conductors that are not used for carrying power to the mounting base  6108  (e.g., wires for data transfer), those conductors may be terminated to the circuit board but not used (e.g., they may be grounded), or they may be terminated to communications circuitry to allow communications between the mounting base  6108  and other devices. The cable  6109  may include other components such as chokes, filters, or the like. The cable  6109  may have a plug or connector at a free end, such as a USB connector, a wall plug, or the like. In some cases, instead of a flexible cable such as the cable  6109 , a power connector (e.g., a plug for a wall outlet) may be incorporated directly with the housing of the housing  6312  of the mounting base  6108 . For example, a plug for a wall outlet may extend from a surface of the housing  6312 . With such a system, a user can plug mounting bases directly into wall outlets and attach tags directly to those bases, thereby providing convenient power and mounting locations for the tags. 
     In some cases, a tag may be programmed, controlled, or communicated with through the mounting base  6108  via the cable  6109 . Further, mounting bases may include additional components or circuitry that supplements that of an attached tag. For example, the mounting base  6108  may include communications systems (wired or wireless) that the tag lacks, or communications systems with a longer wireless range than the tag itself. In such cases, the tag may communicate with other devices (e.g., phones, computers, other tags) through the communications circuitry of the mounting base. 
     The circuit board  6306  may include other electronic components, such as processors, memory, power control circuitry, communications circuitry, or any other components that facilitate operation of the mounting base  6108  and/or an attached tag. 
     The housing  6312  may also define a barometric vent  6313 . The barometric vent  6313  may be an opening that fluidly couples an interior volume of the mounting base  6108  to the exterior environment. As shown, the barometric vent  6313  fluidly couples the interior volume of the mounting base to the opening  6311 . The opening  6311  may be fluidly coupled with the exterior environment even when the cable  6109  extends through the opening  6311 . The barometric vent  6313  facilitates the equalization of pressure between the interior volume of the mounting base  6108 , as well as the interior volume of an attached tag, and the exterior environment. The barometric vent  6313  may include other components such as screens, waterproof and air-permeable membranes, and the like. Further, the barometric vent  6313  may be positioned elsewhere on the housing  6312 , such as through a bottom wall or side wall of the housing  6312 . 
     The contact block  6112  may be attached to the housing  6312  and the circuit board  6306  via adhesive layers  6302 ,  6304 , respectively. The adhesive layers (as well as the circuit board  6306 ) may include openings, gaps, or discontinuities, or otherwise be configured so that air can pass between an attached tag and the interior volume of the housing  6312 , thereby facilitating pressure equalization throughout the assembly. 
       FIG.  64    shows an exploded view of a portion of the mounting base  6108 , showing the contact block  6112  and the first and second conductive members  6202 ,  6204 . The first and second conductive members  6202 ,  6204  may be positioned in openings, recesses, cavities, or other features in the contact block  6112 , and may be conductively coupled to the circuit board  6306  ( FIG.  63   ) so that electrical power can be supplied to an attached tag through the first and second conductive members  6202 ,  6204 . The first and second conductive members  6202 ,  6204  may be secured to the contact block  6112  via adhesives, fasteners, or the like. In some cases, the first and second conductive members  6202 ,  6204  are insert molded with the contact block  6112 , thereby securing the first and second conductive members  6202 ,  6204  to the contact block  6112  and forming an integrated assembly. 
     The first and/or second conductive members  6202 ,  6204  may be deflectable and/or deformable, and may be biased towards the battery connector of a tag to facilitate intimate contact between the first and/or second conductive members  6202 ,  6204  and the battery connector to ensure electrical conductivity between the deflectable arms and the conductive members.  FIGS.  65 A- 65 B  illustrate partial cross-sectional views of the mounting base  6108  with the tag  6102  coupled to the mounting base  6108  such that the first and second conductive members  6202 ,  6204  contact the deflectable arms of a battery connector. For ease of illustration and understanding, some components of the mounting base  6108  and the tag  6102  are omitted or modified. Further, while the tag  6102  may be an embodiment of the tag  500 , some of the components (e.g., the battery connector, the first and second conductive members  6202 ,  6204 ) may be modified for clarity and/or to aid in illustration and explanation. It will be understood that the features, functions, and/or principles shown and described with respect to the tag  6102  in  FIGS.  65 A- 65 B  apply equally to the tag  500  and its specific components and configurations. 
       FIG.  65 A  illustrates a partial cross-sectional view through a portion of the mounting base  6108  and tag  6102  where a first conductive member  6202  contacts a first deflectable arm  6508  of a battery connector  6506  of the tag  6102 . The battery connector  6506  may be an embodiment of the battery connector  900  ( FIG.  9   ), and may be attached to a circuit board  6504 , which may be an embodiment of the circuit board  510  ( FIG.  5 B ). At least a portion of the first deflectable arm  6508  may extend through an opening in a frame member  6502  of the tag, which may be an embodiment of the frame member  512  ( FIG.  5 B ), to allow the first deflectable arm  6508  to contact the first conductive member  6202 . 
     The first deflectable arm  6508  may be biased downwards, while the first conductive member  6202  may be biased upwards. When the tag  6102  is coupled to the mounting base  6108 , the first deflectable arm  6508  may be deflected upwards by the first conductive member  6202 . In some cases, the first conductive member  6202  may be deflected downwards by the first deflectable arm  6508  (and/or it may be deflected downwards by a surface of the tag, such as a surface of the frame member  6502 ). The biasing forces of the first deflectable arm  6508  and the first conductive member  6202  thus force the first deflectable arm  6508  and first conductive member  6202  into contact with one another. 
     Additionally, the first conductive member  6202  may contact the bottom surface of the frame member  6502 , thereby forcing the tag  6102  generally upwards relative to the mounting base  6108 . This upward force on the tag  6102  may help retain the tag  6102  to the mounting base  6108 . For example, as described above, a biasing force between the bottom housing member and the main body portion of a tag may provide a force that maintains the latch members of the bottom housing member in a secure engagement with the engagement features (e.g., recesses) of the tag. When the battery door is attached to the tag, this biasing force may be provided by a compliant member, such as the compliant member  518  ( FIG.  5 B ). Accordingly, the first conductive member  6202  may provide a similar biasing force against the tag  6102  to maintain the engagement between the latch members  6110  and the tag  6102 . 
       FIG.  65 B  illustrates a partial cross-sectional view through a portion of the mounting base  6108  and tag  6102  where a second conductive member  6204  contacts a second deflectable arm  6510  of a battery connector  6506  of the tag  6102 . At least a portion of the second deflectable arm  6510  may extend through an opening in a frame member  6502  of the tag to allow the second deflectable arm  6510  to contact the second conductive member  6204 . 
     The second deflectable arm  6510  may be biased towards the battery cavity (e.g., to the right in  FIG.  65 B ). The second conductive member  6204  may be static (e.g., not deflectable and/or not biased in any particular direction), or it may be biased towards the second deflectable arm  6510  (e.g., to the left in  FIG.  65 B ). The biasing force of the second deflectable arm  6510  may facilitate intimate contact between the second deflectable arm  6510  and the second conductive member  6204  to ensure electrical conductivity between the second deflectable arm  6510  and the second conductive member  6204 . 
     The mounting base  6108  uses latch members  6110  to couple to the tag  6102 . As noted, the latch members  6110  may be configured substantially the same as the latch members of the battery door used for the tag  6102 . Thus, the operation of coupling the tag  6102  to the mounting base  6108  may be the same as or similar to the operation of coupling the battery door to the tag  6102 . Where the tag  6102  is an embodiment of the tag  500 , this may include pressing the tag  6102  and the mounting base  6108  together axially, and then twisting the tag  6102  relative to the mounting base  6108  to engage the latch members  6110  with a recess or undercut region that traps the latch members  6110  to retain the tag  6102  to the mounting base  6108 . Other types of fastening mechanisms may be used instead of or in addition to the latch members  6110 . For example,  FIGS.  66 - 67    illustrate several other examples of mounting bases that use different techniques to couple to a tag. 
       FIG.  66    illustrates an example mounting base  6600  that is configured to semi-permanently attach to a tag, such as the tag  6102 . In particular, instead of latch members that are configured to operate substantially identically to the latch members of the tag&#39;s battery door, the mounting base  6600  is configured so that the tag cannot be detached without breaking or risking breaking the tag and/or the mounting base  6600 . To accomplish this, the mounting base  6600  may include latch members  6604  and blocking features  6602  proximate the latch members  6604 . The latch members  6604  may be configured to engage a channel, ledge, recess, or other feature of the tag such that the tag is axially retained to the mounting base  6600 . The blocking features  6602  may also engage the tag to prevent or inhibit rotational movement of the tag. In this way, it may be difficult or impossible to rotate the tag relative to the mounting base  6600  in a way that will non-destructively disengage the latch members  6604  from the tag. Further, the latch members  6604  may not be accessible to a user to allow the user to disengage the latch members  6604  from the tag. Accordingly, the tag may be securely retained to the mounting base  6600 . This may be useful in instances where the tags are to be used with the mounting base  6600  indefinitely, and/or are installed in static locations or displays. For example, the mounting base  6600  may be used to secure a tag to or near a fire extinguisher, emergency exit, exhibit (e.g., in a museum), retail display, or the like. The mounting base  6600  may provide power to the battery using a contact block as described with respect to other mounting bases described herein. 
       FIG.  67    illustrates an example mounting base  6710  that is configured to attach to a tag using a threaded attachment system. In particular, a tag, which is otherwise similar to the tag  6102 , may include a threaded interface (e.g., a threaded recess) that may be used to attach a battery door with a corresponding threaded feature. Accordingly, the mounting base  6710  may include or define a threaded feature  6714  (e.g., a threaded cylinder) that is configured to engage the corresponding threaded feature of a wirelessly locatable tag. The mounting base  6710  may include latching features, such as pawls, that semi-permanently retain the tag to the mounting base. For example, one or more pawls of the mounting base  6710  may engage the tag when the tag is threaded onto the mounting base  6710 , thereby inhibiting the tag from being un-threaded from the mounting base  6710  (without risking damage to the tag and/or the mounting base). Such features may be implemented for applications where the tag is not meant to be removed from the mounting base  6710  such as permanent installations in buildings, museums, retail displays, or the like. The mounting base  6710  may provide power to the battery using a contact block as described with respect to other mounting bases described herein. 
     While example mounting bases are described as engaging with the same features that are used to attach a battery door to the tag, this is not necessarily required. Rather, in some cases a battery door and a mounting base may attach to a tag using different mounting features or techniques. For example, a battery door may attach to a tag using an engagement between a latch member and a recess, while a mounting base may attach to the same tag using a threaded feature of the tag. 
       FIG.  68    illustrates an example contact block  6800  that is configured to engage the battery connector of a tag to provide power to the battery connector. The contact block  6800  may be used as an alternative to the contact block  6112 , and may be incorporated into any suitable mounting base, such as the mounting bases described herein. The contact block  6800  includes a first conductive member  6802  positioned on a top surface of the contact block  6800  and configured to engage a deflectable arm of a battery connector (e.g., the deflectable arm  6508 ,  FIG.  65 A ). The first conductive member  6802  may have a disk-like shape, and may define all or substantially all of the top surface of the contact block  6800 . Because the first conductive member  6802  has a continuous surface around the top of the contact block  6800 , the first conductive member  6802  will contact the battery connector regardless of the rotational position of the tag relative to the contact block  6800 . The contact block  6800  may also include second conductive members  6804 , which may be configured substantially the same as other second conductive members described herein (e.g., the second conductive members  6204 ). In some cases, instead of multiple discontinuous second conductive members  6804 , a single second conductive member  6804  may extend annularly around the periphery of the contact block  6800 , thereby ensuring that a portion of the second conductive member  6804  will contact the battery connector of the tag regardless of the rotational position of the tag relative to the contact block  6800 . 
     The contact block  6800  may also include a biasing member  6806  that is configured to apply a biasing force on the tag. As described above, a biasing force from a contact block may force latch members of a contact block into engagement with corresponding features of a tag. The biasing member  6806  may be a spring, foam, elastomer, or any other suitable material or component that can apply the requisite biasing force to the tag. 
     The foregoing example mounting bases describe some example features and/or mechanisms for attaching to tags. Of course, other configurations are also contemplated. For example, the features or members that are described as being on a mounting base may be provided on a tag instead, and the tag&#39;s features may instead be on the corresponding mounting base. Further, where tags use other types of mechanisms to retain a battery door or other housing member, a mounting base may use the same type of mechanism to attach to that tag. 
     One advantage of the size and form factor of the tags described herein is that they can be securely attached to numerous types of accessories using numerous attachment techniques and components. For example, accessories may be provided that allow the tag to be attached to a key ring (also referred to herein as a split ring), a wallet, a briefcase, a purse, an article of clothing, luggage, a notebook or tablet computer, a pet&#39;s collar, or any other item that a user desires to track with a wirelessly locatable tag, as described herein. 
       FIGS.  69 A- 128    illustrate various example accessories and attachment techniques that may be used with the tags described herein.  FIGS.  69 A- 69 C , for example, illustrate an example tag retainer  6900  for holding a tag, such as the tag  300  ( FIG.  3   ) or any other tag embodiment described herein. The tag retainer  6900  may also be referred to as a holder, tag holder, tag accessory, or simply accessory. The tag retainer  6900  may include a tag receptacle portion  6902  and an attachment portion  6904  (which may be or may resemble a strap and may be referred to herein as a strap or a fastening strap). The tag receptacle portion  6902  is configured to receive and hold the tag  300  securely, and the attachment portion  6904  is configured to attach the tag retainer  6900  to another object. The tag receptacle portion  6902  may also be referred to as a pocket, recess, or tag retaining feature. As shown in  FIGS.  69 A- 69 B , the attachment portion  6904  is attached to a split ring  6906 , though this is merely one example object to which it could be attached. For example, the attachment portion  6904  may be attached to a luggage or purse handle, a pet collar, or any other suitable object. 
     The tag retainer  6900  may define an opening  6910 , defined along less than a complete circumference of the tag receptacle portion  6902 , that allows the tag  300  to be placed in and removed from the tag retainer  6900 . The tag retainer  6900  also includes a fastener  6908  that is configured to releasably secure the opening  6910  in a closed position. The fastener  6908  may also be configured to secure the attachment portion  6904  in a closed or looped position (as shown in  FIGS.  69 A- 69 C ) to couple the attachment portion  6904  (fastening strap) to another object, such as the split ring  6906 . The fastener  6908  may permanently secure the end of the attachment portion  6904  to the base of the attachment portion  6904  (thereby permanently forming the loop in the attachment portion  6904 ), or it may releasably secure the end of the attachment portion  6904  to the base of the attachment portion  6904  such that the loop can be selectively opened or closed (so the attachment portion  6904  can be easily attached to or detached from an object such as the split ring  6906 , a suitcase or briefcase, or the like). 
     The fastener  6908  may be a snap, clip, button, or any other suitable fastener. In some cases, the fastener  6908  includes multiple snap elements to allow the opening  6910  in the tag receptacle portion  6902  to be fastened and unfastened independently of the loop formed in the attachment portion  6904 . Stated another way, the loop in the attachment portion  6904  may be fastened and unfastened (e.g., to allow the tag retainer  6900  to be attached to or detached from other objects) while the opening  6910  remains fastened closed. 
     The tag receptacle portion  6902  may define a circular cavity in which the tag  300  is placed. The circular cavity may have a size and shape that generally corresponds to that of the tag  300 , such that the surface of the tag receptacle portion  6902  that defines the cavity (e.g., the inner surface of the receptacle portion) touches and/or is in intimate contact with the exterior surfaces of the tag  300  when the tag  300  is in the cavity. This may help prevent movement of the tag  300  within the cavity and help secure the tag  300  in the cavity. Thus, for example, the size and shape of the cavity may be the same as or substantially the same as the size and shape of the tag  300 . 
     The tag receptacle portion  6902  may have one or more openings  6912  that allow a user to see into the tag receptacle portion  6902  and easily determine if the tag  300  is or is not currently in the tag receptacle portion  6902 . The openings  6912  may also allow speakers, microphones, environmental sensors, and/or other inputs and/or outputs of the tag  300  to access the outside environment. For example, at least one of the openings  6912  may be aligned with a portion of a tag housing that acts as a speaker diaphragm. In this manner, the surface of the housing that moves to produce audible and/or tactile outputs may be exposed and/or un-occluded so that audible and/or tactile outputs are not inhibited. The openings  6912  may be specifically configured in view of the tag  300  (or any tag for which the retainer  6900  is designed) to have sizes and/or shapes that are smaller than the tag  300 , such that the tag  300  cannot fall out of the tag retainer  690  through the openings  6912 . For example, the openings  6912  may be circular openings with a diameter that is less than the largest diameter of a circular tag. In some cases, the diameters (or the largest dimension) of the openings  6912  are less than about 3 inches, less than about 2 inches, or less than about 1 inch. Other embodiments may be completely enclosed or otherwise not provide visual access to the inside of the tag receptacle portion  6902 . 
     The tag retainer  6900  may be formed from or include any suitable materials. For example, the tag retainer  6900  may be formed from leather, polymer (e.g., silicone, thermoplastic polyurethane (TPU)), fabric or cloth, or the like. If the tag retainer  6900  is formed of polymer, it may be formed as a single unitary polymer part (with the exception of the fastener  6908 ). The tag retainer  6900  may also be formed by joining multiple different layers, materials, and/or parts together. For example, the tag receptacle portion  6902  may include a first layer that defines a first portion of the tag receptacle portion  6902  (and optionally including the attachment portion  6904 ), and a second portion that defines a second portion of the tag receptacle portion  6902 . The first layer may correspond to the material on the left side of the vertical seam shown in  FIGS.  69 A and  69 B  (e.g., the seam that defines and/or corresponds to the opening  6910 ), while the second layer may correspond to the material on the right side of the vertical seam. The first and second layers of the tag retainer  6900  may each include one layer of material, or they may each be formed of multiple sublayers of materials, with the sublayers being attached to one another (e.g., laminated) using adhesives, ultrasonic welding, laser welding, stitching, insert molding, or any other suitable technique. 
     The first and second layers may be sewn, stitched, adhered, or otherwise coupled together around part of the circumference of the tag receptacle portion  6902  to join the first and second layers while also defining the opening  6910  that allows the tag  300  to be inserted into and removed from the tag receptacle portion  6902 . For example, the first layer may be adjacent the second layer along an interface region (e.g., the surfaces of the first and second layers that face and/or abut one another when the tag retainer  6900  is assembled and closed). The second layer may be attached to the first layer along a first segment of the interface region (e.g., around the bottom portion of the tag retainer, as illustrated in  FIGS.  69 B- 69 C  by the absence of a seam or line between the left and right portions), and may be unattached to the first layer along a second segment of the interface region, thereby defining the opening  6910  between the first layer and the second layer. 
       FIGS.  69 D- 69 G  illustrate another example tag retainer  6920  that is similar to the tag retainer  6900 , but secures the tag retainer in a closed configuration using a strap interlaced with a tab, instead of a fastener such as a snap. The tag retainer  6920  may otherwise be substantially similar to the tag retainer  6900 . The details of the tag retainer  6900  apply equally or by analogy to the tag retainer  6920 , and may not be repeated here to avoid redundancy. 
     The tag retainer  6920  may include a tag receptacle portion  6922  and an attachment portion or strap  6926 . The tag receptacle portion  6922  is configured to receive and hold the tag  300  securely, and the strap  6926  is configured to attach the tag retainer  6920  to another object. As shown in  FIGS.  69 D and  69 G , the strap  6926  is attached to a split ring  6934  (which passes through a loop  6932  at a terminal end of the strap  6926 ), though this is merely one example object to which it could be attached. For example, the strap  6926  may be attached to a luggage or purse handle, a pet collar, or any other suitable object. The strap  6926  extends from the tag receptacle portion  6922  proximate the first opening  6929 . 
     The tag retainer  6920  may define an opening  6929 , defined along less than a complete circumference of the tag receptacle portion  6922 , that allows the tag  300  to be placed in and removed from the tag retainer  6920 . The tag retainer  6920  also includes a tab  6928  extending from the tag receptacle portion  6922  proximate the first opening  6929 . The tab  6928  defines a strap opening  6930 , that is configured to receive the strap  6926  therethrough (e.g., the strap  6926  is configured to extend through the opening  6930 ) to retain the first opening  6929  in a closed configuration. The strap  6926  is also configured to be removed from the strap opening  6930  to allow the first opening  6929  to expand to accept the tag  300 . 
     The split ring  6934  may be removed from the strap  6926  to facilitate passing the strap  6926  through the opening  6930  and/or removing the strap  6926  from the opening  6930 . When attached to the strap  6926 , the size of the split ring  6934  may prevent the strap  6926  from being removed from the opening  6930 , thereby maintaining the opening  6929  in a closed configuration. For example, a dimension of the split ring  6934  (e.g., a diameter) is larger than a dimension of the opening  6930  (e.g., a largest linear dimension of the opening), thereby preventing the terminal end of the strap  6926  from passing through the opening  6930  when the split ring  6934  is attached to the loop  6932  of the strap  6926 .  FIG.  69 E  shows the tag retainer  6920  with the opening  6929  in an open configuration to receive the tag  300 . In this configuration, the strap  6926  is not extended through the opening  6930 .  FIG.  69 F  shows the tag retainer  6920  with the opening  6929  in a closed configuration, after the strap  6926  has been passed through the opening  6930 .  FIG.  69 G  shows the tag retainer  6920  after the split ring  6934  has been attached to the strap  6926  (through the loop  6932 ). In the configuration of  FIG.  69 G , the opening  6929  may be retained in a closed configuration by the interference of the split ring  6934  with the opening  6930 . By retaining the opening  6929  closed, inadvertent opening of the tag receptacle portion  6922  and release of the tag  300  may be prevented or inhibited. 
     The tag receptacle portion  6922  may define a circular cavity in which the tag  300  is placed. The circular cavity may have a size and shape that generally corresponds to that of the tag  300 , such that the surface of the tag receptacle portion  6922  that defines the cavity (e.g., the inner surface of the tag receptacle portion  6922 ) touches and/or is in intimate contact with the exterior surfaces of the tag  300  when the tag  300  is in the cavity. This may help prevent movement of the tag  300  within the cavity and help secure the tag  300  in the cavity. Thus, for example, the size and shape of the cavity may be the same as or substantially the same as the size and shape of the tag  300 . 
     The tag receptacle portion  6922  may have one or more openings  6924  that allow a user to see into the tag receptacle portion  6922  and easily determine if the tag  300  is or is not currently in the tag receptacle portion  6922 . The openings  6924  may also allow speakers, microphones, environmental sensors, and/or other inputs and/or outputs of the tag  300  to access the outside environment. For example, at least one of the openings  6924  may be aligned with a portion of a tag housing that acts as a speaker diaphragm. In this manner, the surface of the housing that moves to produce audible and/or tactile outputs may be exposed and/or un-occluded so that audible and/or tactile outputs are not inhibited. Other embodiments may be completely enclosed or otherwise not provide visual access to the inside of the tag receptacle portion  6922 . 
       FIGS.  70 A- 70 D  illustrate an example tag retainer  7000 , which is similar to the tag retainer  6900  but has a different attachment portion. In particular, while the attachment portion  6904  of the tag retainer  6900  is configured to be releasably secured in a loop by a mechanical fastener  6908 , the tag retainer  7000  includes an attachment portion  7004  that defines an opening  7006  that allows the attachment portion  7004  to define a loop with itself. For example,  FIG.  70 D  illustrates how the attachment portion  7004  can be formed into a loop using the opening  7006  by passing the tag receptacle portion  7002  through the opening  7006 . The attachment portion  7004  may be used to fasten the tag retainer  7000  to any suitable object such as a key ring, purse, luggage handle, or the like. 
     The tag retainer  7000  may otherwise be similar in construction and use to the tag retainer  6900 . For example,  FIG.  70 C  shows how the tag retainer  7000  may be opened (at opening  7010 ) to allow the tag  300  to be placed in and/or removed from the tag receptacle portion  7002 . Further, the tag retainer  7000  may define openings (e.g., circular openings) that allow speakers, microphones, environmental sensors, and/or other inputs and/or outputs of the tag  300  to access the outside environment. The tag retainer  7000  may include a fastener  7008  that is configured to releasably secure the opening  7010  in a closed position (as shown in  FIGS.  70 B and  70 D ). The fastener  7008  may be a snap, button, or any other suitable fastening mechanism. In some cases, the tag retainer  7000  may selectively retain its opening  7010  in the closed configuration using an arrangement as shown in  FIGS.  69 D- 69 G  (e.g., a tab with an opening configured to receive the strap or attachment portion  7004 ). Other details of the tag retainer  7000  may be the same as or similar to those of the tag retainer  6900 , and for brevity may not be repeated here. 
       FIGS.  71 A- 71 C  illustrate an example tag retainer  7100 .  FIG.  71 A  illustrates a top perspective view of the tag retainer  7100 , and  FIG.  71 B  illustrates a bottom view of the tag retainer  7100 . The tag retainer  7100  may act as a protective shell for a tag, and may also facilitate the attachment of the tag to other components. The tag retainer  7100  may be formed from a flexible and/or compliant material so that the tag retainer  7100  can be stretched or otherwise deformed to allow the tag  300  to be inserted into and removed from the tag retainer  7100 . For example, the tag retainer  7100  may be formed from or include silicone, TPU, or another suitable polymer or other material. The tag retainer  7100  may be formed from a unitary piece of a single material. 
     The tag retainer  7100  may include a tag receptacle portion  7102  and a gripping portion  7104  (which may be used to grip the tag retainer and/or attach the tag retainer to another object). The tag receptacle portion  7102  may define a first opening  7106  along a first side of the tag receptacle portion  7102  and a second opening  7108  along a second side of the tag receptacle portion  7102 . The first opening  7106  may be sized and configured so that a battery door of the tag  300  extends into the first opening  7106  when the tag  300  is positioned in the tag retainer  7100 , and may be smaller than the second opening  7108 . As shown in  FIG.  71 C , which is a partial cross-sectional view of the tag retainer  7100 , viewed along line  71 C- 71 C in  FIG.  71 A , the thickness of the material that defines the perimeter of the tag receptacle portion  7102  may be substantially equal to the distance that the battery door extends above the surface of the main body portion of the tag  300 . Accordingly, an exterior surface of the tag receptacle portion  7102  proximate the first opening  7106  may be substantially flush with the surface of the battery door. 
     The second opening  7108  may be sized and configured to allow the tag  300  to be placed in and removed from the tag retainer  7100 . The second opening  7108  may be at least partially defined by or proximate to a tag retention feature  7110  that contacts the tag  300  and retains the tag  300  in the tag retainer  7100 . The tag retention feature  7110  may be or resemble a lip, flange, protrusion, or other feature. The tag retention feature  7110  may extend around the entire circumference of the second opening  7108 . 
     The tag  300  may be inserted into and removed from the tag retainer  7100  by deforming or stretching the second opening  7108  so that the tag  300  can be fit into the tag retainer  7100 . The first and second openings  7106 ,  7108  may be configured to allow speakers, microphones, environmental sensors, and/or other inputs and/or outputs of the tag  300  to access the outside environment when the tag  300  is placed in the tag retainer  7100 . 
     The tag retainer  7100  may also define a flange  7103  that extends at least partially (and optionally completely) around the outer periphery of the tag retainer  7100 . The flange  7103  may allow the tag retainer  7100  to be attached to other objects. For example, the flange  7103  may be sewn, adhered, bonded, or otherwise attached to another object such as an article of clothing, a purse, a wallet, or the like. The gripping portion  7104  may be considered an extension of or enlarged portion of the flange  7103 . The tag retainer  7100  may also define a vent similar to the vent  7204  ( FIGS.  72 A- 72 C ) to allow sound waves, which may be produced by moving the housing member of the tag  300 , to escape a volume defined between space between the tag  300  and a surface to which it is attached. 
       FIGS.  72 A- 72 C  illustrate an example tag retainer  7200 .  FIG.  72 A  illustrates a top perspective view of the tag retainer  7200 , and  FIG.  72 B  illustrates a bottom view of the tag retainer  7200 .  FIG.  72 C  is a partial cross-sectional view of the tag retainer  7200 , viewed along line  72 C- 72 C in  FIG.  72 A . The tag retainer  7200  may be similar in size and construction to the tag retainer  7100  (but without the grip portion). For example, the tag retainer  7200  may be formed from or include silicone, TPU, or another suitable polymer or other material. The tag retainer  7200  may be formed from a unitary piece of a single material. 
     The tag retainer  7200  defines a first opening  7202  that at least partially receives a battery door of the tag  300  (similar to the first opening  7106  of the tag retainer  7100 ) and a second opening  7206  that allows the tag  300  to be inserted into and removed from the tag retainer  7200 . Similar to the tag retainer  7100 , the second opening  7206  may be at least partially defined by or proximate to a tag retention feature  7208  (e.g., a lip, flange, protrusion) that contacts the tag  300  and retains the tag  300  in the tag retainer  7200 . 
     The tag retainer  7200  may be adapted to be adhered to other components along a bottom surface  7210  of the tag retainer  7200 . For example, an adhesive layer may be applied to the bottom surface  7210  to allow the tag retainer  7200  to be adhered to another object after the tag  300  is inserted into the tag retainer  7200 . In some cases the adhesive may include a tear-away backing so that the tag retainer  7200  may be sold with the adhesive attached. A user can then simply place a tag  300  into the tag retainer  7200 , remove the backing, and adhere the tag retainer  7200  to an object (e.g., a computer, luggage, a mobile phone, etc.). 
     The tag retainer  7200  may define a vent  7204  along the bottom surface  7210 . The vent  7204  may fluidly couple the external environment around the tag retainer  7200  to the space defined between an outer surface  7211  of the tag  300  and the surface on which the tag retainer  7200  is mounted. This may allow sound produced by the tag  300  to be transmitted more effectively to the outside environment. More particularly, as described above, the tag  300  may include an audio system that produces audible output, optionally using the outer surface  7211  of the tag  300  as a speaker diaphragm. The vent  7204  may allow air pressure waves to exit the otherwise enclosed space between the tag  300  and the surface to which it is attached, so that the sounds can be more easily heard (e.g., the vent  7204  reduces the sound attenuation as compared to an un-vented tag retainer  7200 ). The size and shape of the tag retainer  7200  may be configured so that the volume defined between the outer surface  7211  of the tag  300  and a surface to which the tag retainer  7200  is attached operates as a Helmholtz resonator, or is otherwise tuned to provide satisfactory acoustic performance. 
     As noted above, the size and shape of the tags described herein may allow the tags to be secured to accessories in various different ways. For example, the tag retainers  6900  and  7000  contact the tag on multiple sides to partially (or fully) enclose the tag. The tag retainers  7100 ,  7200  have circumferential tag retention features (e.g., a circular lip around an opening) that retain a tag in the tag retainers. However, numerous other techniques for retaining a tag are also contemplated. As used herein, the structures and/or components used to retain a tag to an accessory or another object may be referred to as “tag retainers.” Thus, the tag retention features  7110  and  7208  may be examples of tag retainers.  FIGS.  73 A- 128    show numerous examples of tag retainers. For simplicity,  FIGS.  73 A- 128    show examples of tag retainers in the context of one example accessory (an accessory with an elongated segment for forming a loop around a key ring, as one example), though it will be understood that any of the tag retainers shown in FIGS.  73 A- 128  may be used with other types of accessories as well. For example, a tag retainer that is used in a keychain accessory may instead be incorporated with a luggage-attachment accessory. 
       FIG.  73 A  depicts an example tag retainer  7300  that includes a body  7302  and one or more retention flanges  7304  secured to the body  7302 , where the retention flanges  7304  have a greater stiffness than the body  7302 . The retention flanges  7304  may be configured to extend at least partially into a gap or channel between a battery door and a main body portion of a tag to retain the tag to an accessory. The increased stiffness of the retention flanges  7304  relative to the body  7302  helps increase the strength and security of the attachment. As used herein, the gap between the battery door and the main body portion of a tag may be referred to as a “housing gap.” Further, a housing gap of a tag need not be defined by a battery door and a main body portion, and instead may be defined between other components of a tag (e.g., two housing members, neither of which operate as a battery door). 
     When installing a tag into the tag retainer  7300 , the body  7302  may be configured to stretch to allow an opening of the body  7302  to be enlarged to accommodate the tag, and then return to an un-stretched (or less stretched) configuration to bias the retention flanges  7304  into the housing gap. The retention flanges  7304  may be snapped into and out of position in the housing gap when inserting and removing the tag  300 . 
       FIG.  73 B  is a partial cross-sectional view of the tag retainer  7300  of  FIG.  73 A , viewed along line  73 B- 73 B in  FIG.  73 A , showing how the tag  300  may be installed and retained in the tag retainer  7300 . As shown, the tag  300  defines a gap  7306  between part of a battery door and a main body portion of the tag  300  (e.g., a housing gap). The retention flanges  7304  are configured so that a portion of the retention flanges  7304  extend into the housing gap  7306  to retain the tag  300  in the tag retainer  7300 . 
     The retention flanges  7304  may be attached to the body  7302  in any suitable way. For example, the retention flanges  7304  may be inserted into a mold, and then material for the body  7302  may be injected into the mold to at least partially encapsulate the retention flanges  7304  and retain the retention flanges  7304  to the body  7302 . The retention flanges  7304  may also be adhered to the body  7302  or secured in any other suitable way. 
       FIGS.  74 A- 74 F  illustrate an example tag retainer  7400  that includes a spring member  7404  embedded in a body  7402 . The body  7402  may be formed from a compliant, flexible material or materials (such as silicone, TPU, or another suitable polymer), and the spring member  7404  may be formed from a material having a higher stiffness, such as a metal (e.g., spring steel) or less flexible polymer. The body  7402  and the spring member  7404  may cooperate to engage a housing gap of a tag. In particular, as shown in  FIG.  74 A , the body  7402  is biased into a housing gap of a tag by the spring member  7404 . To more clearly illustrate how the tag retainer  7400  engages the tag  300 ,  FIG.  74 A  illustrates a sectional view of the tag  300 , showing the tag  300  without an upper portion of the battery door. (The section line  7403  of the tag  300  is shown in  FIG.  74 C .) 
     In order to attach or detach the tag  300  from the tag retainer  7400 , the tag retainer  7400  is manipulated so that the spring member  7404  and the body  7402  can expand. For example, a force applied to the body  7402  (indicated by arrows  7407 ) may force engagement ends  7410  of the spring member  7404  against the tag  300 , thereby allowing the engagement ends  7410  to spread apart, ultimately enlarging the opening in the body  7402  to allow the tag  300  to be more easily removed from or inserted into the opening. 
       FIGS.  74 C- 74 F  are partial cross-sectional views of the tag retainer  7400  and the tag  300  of  FIG.  74 A , viewed along line  74 C- 74 C in  FIG.  74 A , illustrating an example process for disengaging the tag  300  from the tag retainer  7400 . In  FIG.  74 C , the tag  300  is positioned in an opening of the tag retainer  7400  such that the a portion of the body  7402  of the tag retainer  7400  is positioned in a housing gap, thereby retaining the tag  300  to the tag retainer  7400 . The spring member  7404  biases the body  7402  into the housing gap, as described above. 
     In  FIG.  74 D , a force is applied to the tag retainer  7400  (and/or the tag  300 ), as indicated by arrows  7409 . (This operation corresponds to  FIG.  74 B .) The force may be applied by grasping the tag  300  and/or the tag retainer  7400  in hand and applying a force that tends to move the tag  300  towards the engagement ends  7410  of the spring member  7404 . This operation expands the size of the opening and introduces a gap  7412  between a flap  7408  of the body  7402  and the tag  300 . In  FIG.  74 E , the tag retainer  7400  is angled to disengage the flap  7408  of the body  7402  from the housing gap. When the flap  7408  is removed from the housing gap, the rest of the body  7402  may be easily disengaged from the housing gap to fully remove the tag  300  from the tag retainer  7400 , as shown in  FIG.  74 F . The tag  300  may be coupled to the tag retainer  7400  by reversing these steps. 
     Notably, the force that is required to easily detach the tag  300  from the tag retainer  7400  is in an opposite direction than the types of accidental forces that may be imparted to the tag  300  during use. For example, if the tag retainer  7400  is coupled to a purse via a strap  7411 , if the tag  300  were to snag on another object such as a piece of clothing, the force would tend to pull the tag  300  away from the strap, which is in the opposite direction to the force that is used to decouple the tag  300 . Forces in this direction may actually serve to further tighten or secure the tag  300  to the tag retainer  7400 . In this way, the tag retainer  7400  may allow the tag  300  to be attached and detached easily, while reducing the risk of accidental detachment due to snags and the like. 
     In some cases the tag retainer  7400  may have a stiffening element (or the body  7402  may be formed from a sufficiently stiff material) so that the force applied to the body  7402  may be effectively transferred to the engagement ends  7410  of the spring element. For example, a strap or handle portion of the body  7402  may be formed from or include a metal, plastic, or other material that is stiffer than the portion of the body  7402  that defines the opening and engages the tag  300 . The engagement ends  7410  of the spring member  7404  may define curved regions that are nearer to the tag  300  than other portions of the spring member  7404 . These curved regions may result in a primary body/tag interface at location  7406  ( FIGS.  74 A- 74 B ) during the coupling and decoupling operations. By focusing the force at this location  7406 , a sufficiently large portion of the force applied by a user may be transferred to the spring member  7404  to cause it (and thus the opening) to expand. 
     The spring member  7404  may be at least partially embedded in the body  7402 . For example, the spring member  7404  and the body  7402  may be insert molded to produce the tag retainer  7400 . 
       FIGS.  75 A- 75 C  illustrate a tag retainer  7500  similar to the tag retainer  7400  but with a different spring member configuration. The tag retainer  7500  may include a body  7502 , which may be formed from or include a polymer material or other compliant material (including combinations of materials), and a spring member  7504 , which may be formed from a material with a greater stiffness than the body (e.g., spring steel, a polymer, etc.). The spring member  7504  may define extension ends  7506  that extend away from the opening in the body  7502  and optionally into a handle portion  7513  of the body  7502 . The extension ends  7506  may help increase the stiffness of the body  7502  so that a force applied to the tag retainer  7500  and/or the tag  300  to couple or decouple the tag  300  may be transferred efficiently to the tag/body interface. 
       FIGS.  75 B- 75 C  are partial cross-sectional views of the tag retainer  7500  and the tag  300  of  FIG.  75 A , viewed along line  75 B- 75 B in  FIG.  75 A , illustrating a process of attaching the tag  300  to the tag retainer  7500 . As shown in  FIG.  75 B , a first side of the body  7502  is engaged with the tag  300 , and a force (indicated by arrow  7507 ) is applied to the body  7502  tending to pivot the body  7502  into engagement with the housing gap. The force may cause the spring member  7504 , and thus the opening size, to expand to allow the body  7502  to stretch over the battery door of the tag  300  and engage the housing gap.  FIG.  75 C  shows the tag retainer  7500  fully engaged with the housing gap. 
     The tag retainers  7400  and  7500  each include an example spring member, though alternative types of spring members may be used in their place. For example, a c-clip may be used, and the c-clip may include holes for engaging an opening tool. In such cases, a tag may be coupled by forcing the c-clip open using a tool, inserting the tag into the opening, and removing the tool to allow the c-clip to force the tag retainer to engage the tag. 
       FIGS.  76 A- 76 C  illustrate a tag retainer  7600  with a closed-ring spring member  7604  embedded in a body  7602 . In contrast to the spring members in the tag retainers  7400  and  7500 , which each define two free ends, the closed-ring spring member  7604  defines a continuous, closed ring shape. The body  7602 , and in particular the body material and the size and shape of the opening  7601  may be configured so that the tag can be inserted into and removed from the opening  7601  without the closed-ring spring member  7604  significantly flexing or expanding. Instead, the opening  7601  is slightly larger than the size of the part of the tag that the opening  7601  surrounds. 
       FIGS.  76 B- 76 C  are partial cross-sectional views of the tag retainer  7600  of  FIG.  76 A , viewed along line  76 B- 76 B in  FIG.  76 A , illustrating a process of attaching the tag  300  to the tag retainer  7600 . As shown in  FIG.  76 B , a first side of the body  7602  is engaged with the tag  300  (at location  7606 ) such that the body  7602  contacts the tag  300  at that location, or is otherwise sufficiently close to the tag to allow the other end of the body  7602  to pass over the tag  300  at location  7609  (as indicated by arrow  7607 ). The body  7602  may have sufficient compliance so that it can stretch slightly when the tag  300  is being inserted. 
     Once the tag  300  is in the opening of the tag retainer  7600 , a portion of the body  7602  and the closed-ring spring member  7604  may be positioned in the housing gap under the overhang of the battery door, though there may remain a space  7608  between the body  7602  and the tag  300 , resulting from the larger diameter of the opening  7601  to accommodate the greater stiffness (e.g., lower deformability) of the tag retainer  7600  due to the closed-ring spring member  7604 . 
       FIGS.  77 A- 77 B  illustrate a tag retainer  7700  with another type of spring member  7704  embedded in a body  7702 . In particular, the free ends of the spring member  7704  are crossed over one another to define manipulation ends  7705 . A force can be applied to the manipulation ends  7705  by a user, as indicated by arrows  7707  in  FIG.  77 B , to cause the opening of the tag retainer  7700  to expand. This expansion produces additional space  7706  between the body  7702  and the tag  300  to allow the tag  300  to be attached and/or detached from the tag retainer  7700 . When the force is removed, the spring member  7704  returns to its smaller state, thereby biasing the opening to its un-expanded state to help maintain the tag retainer  7700  in the housing gap and thus keep the tag  300  secured to the tag retainer  7700 . 
       FIGS.  78 A- 78 B  illustrate a tag retainer  7800  with another type of spring member  7804  embedded in a body  7802 . The spring member  7804  may be a circular coil spring that can be expanded when a radial force is applied to the spring member  7804 . Thus, for example, a force can be applied to the tag  300  tending to pull the tag  300  radially outward with respect to the circular spring member  7804 , thereby causing the opening of the tag retainer  7800  to expand (as shown in  FIG.  78 B ). This expansion produces additional space  7806  between the body  7802  and the tag  300  to allow the tag  300  to be attached and/or detached from the tag retainer  7800 . When the force is removed, the spring member  7804  returns to its smaller state, thereby biasing the opening to its un-expanded state to help maintain the tag retainer  7800  in the housing gap and thus keep the tag  300  secured to the tag retainer  7800 . The spring member  7804  may be a conventional coil spring wrapped about the opening. In other cases, the spring member  7804  resembles a flattened coil spring (e.g., the height of the spring member is less than a diameter of the coil loops). 
       FIGS.  79 A- 79 B  illustrate another example tag retainer  7900 . The tag retainer  7900  includes a body  7902  that is formed into a circular end that defines an opening  7901  for receiving a tag therein. The body  7902  may be formed from a stiff core with a soft-touch outer coating. For example, the body  7902  may include a metal internal core with a polymer outer coating, jacket, or layer. Or the body  7902  may be formed from two plastics having different stiffnesses (e.g., a stiffer internal core and a less stiff outer coating). Alternatively, the body  7902  may be formed of a single piece of plastic. The internal core (or the single piece of plastic) may provide a spring-like force to the body  7902  so that the body  7902  can be forced into a configuration where the opening  7901  defines a closed loop (e.g., to attach to a tag), and the spring force can bias the body  7902  into a latched or secured configuration. The internal core may extend through at least the part of the body  7902  that defines the opening  7901 , and optionally through at least part of the clip feature  7904 . 
     The body  7902  includes or defines a clip feature  7904  that can be engaged and disengaged with a retaining portion  7906  of the body  7902  to selectively open or close the circular end. For example,  FIG.  79 B  shows the tag retainer  7900  with the clip feature  7904  disengaged from the retaining portion  7906  of the body  7902 . This shape may correspond to the shape of the body  7902  when no forces are applied to the body  7902  (e.g., the body  7902  is in an unstressed or undeflected state). The opening  7901  in this state may be sufficiently large for the tag  300  to be easily inserted into the opening  7901 .  FIG.  79 C  shows the tag retainer  7900  with the clip feature  7904  engaged with the retaining portion  7906  of the body  7902 , thereby forming a closed loop that retains the tag retainer  7900  to the tag  300 . In this state, the opening  7901  may be smaller so that the body  7902  is retained in the housing gap of the tag  300 . Further, the spring force produced by the body  7902  tends to force the clip feature  7904  away from the retaining portion  7906 , thereby forcing the clip feature  7904  into secure engagement with the retaining portion  7906  (e.g., due to the hook-like shape of the clip feature  7904 ). Detaching the tag  300  from the tag retainer  7900  may be achieved by pulling on the clip feature  7904  so that it can be unhooked from the retaining portion  7906  and allowed to return to its undeflected state (shown in  FIG.  79 B ) and the tag  300  can be removed. 
       FIGS.  80 A- 80 C  illustrate another example tag retainer  8000 . Similar to the tag retainer  7900 , the tag retainer  8000  may rely on a body  8002  that is relatively stiff so that the body can engage a housing gap of a tag to secure the tag to the tag retainer  8000 . In particular, the body  8002  may define an opening  8001  that is biased in an open loop shape, and can be retained in a closed-loop shape via a retention mechanism. 
     To act as a retention mechanism, the tag retainer  8000  includes a clip end  8004  and a post  8006 . The clip end  8004  is configured to engage the post  8006  to retain the opening  8001  in a closed loop configuration.  FIG.  80 A  shows the tag retainer  8000  in an un-clipped, open loop state, while  FIG.  80 B  shows the tag retainer  8000  in a closed loop state and engaging a housing gap of the tag  300 . 
       FIG.  80 C  is a partial cross-sectional view of the tag retainer  8000 , viewed along line  80 C- 80 C in  FIG.  80 B , showing the clip end  8004  engaged with the post  8006  to maintain the opening  8001  in a closed state and retain the tag  300 . The clip end  8004  may include or define recesses  8012  with undercuts. The post  8006  may extend at least partially into the recesses  8012  such that a flange  8010  or lip element of the post  8006  engages the undercut of the recesses  8012  to retain the clip end  8004  to the post  8006 . In some cases, the clip end  8004  and the post  8006  may use magnetic attraction to help retain the clip end  8004  to the post  8006 . For example, the post  8006  may be formed from or include a magnet, and the clip end  8004  may include ferromagnetic elements  8008  (e.g., steel inserts) that are attracted to the magnetic post  8006 . Other configurations and positions of magnets, ferromagnetic materials, etc., are also contemplated. The magnetic attraction between the clip end  8004  and the post  8006  may provide several functions. For example, it may help snap the clip end  8004  and the post  8006  into an engaged position, thereby simplifying the attachment process. Additionally, it may retain the clip end  8004  and the post  8006  together during use, and may help maintain the engagement between the flange of the post  8006  and the undercuts of the recesses  8012  (which may provide greater security against decoupling than the magnetic attraction alone). 
       FIGS.  81 A- 81 B  illustrate an example tag retainer  8100  in which a body  8102  forms a loop around a tag, and is secured by a post and hole fastening system. In particular, the tag retainer  8100  includes a post  8106  and the body  8102  defines an opening  8104  configured to receive the post  8106 . When the post  8106  is inserted into the opening  8104 , the body  8102  defines a loop that surrounds the tag  300  ( FIG.  81 B ) in the housing gap of the tag  300 . The post  8106  may define a free end that is larger than the opening  8104  and a shaft that is smaller than the free end. The free end may deform the opening  8104  when the post is pushed into the opening  8104 , and the opening  8104  may undeform after the post  8106  is inserted, thus causing the opening  8104  and the shaft of the post  8106  to engage, with the free end serving as a retention feature that retains the post  8106  in the opening  8104  (and thus retains the tag retainer  8100  in a loop that holds the tag  300 ). 
       FIGS.  82 A- 82 B  illustrate an example tag retainer  8200  in which a loop is secured around a tag with a slider.  FIG.  82 A  shows the tag retainer  8200 , which may include a cord  8202  formed into a loop  8201  and wrapped around the tag  300 . To secure the tag retainer  8200  to the tag  300 , a user may slide the slider  8204  towards the tag  300 , thereby tightening the loop  8201  around the tag  300  (and within the housing gap), as shown in  FIG.  82 B . The tightened loop  8201  in the housing gap provides sufficient engagement with the tag  300  to retain the tag  300  to the tag retainer  8200 . The slider  8204  may be configured so that friction between holes in the slider  8204  and the cord  8202  (which may extend through the holes) is sufficient to prevent accidental movement of the slider  8204 , thereby maintaining the loop  8201  in a tightened state. In other cases the slider  8204  may include a locking mechanism, such as a cam lock, clamp, cord lock, releasable ratcheting mechanism (e.g., similar to a zip tie), or the like, to help prevent the slider  8204  from moving unintentionally. 
       FIGS.  83 A- 83 B  illustrate an example tag retainer  8300  in which a loop is secured around a tag with a slider. The tag retainer  8300  is similar to the tag retainer  8200 , except that instead of a single cord with two free ends defining the loop, the tag retainer  8300  includes a body  8302  that defines a closed loop opening  8306 . A slider  8304  may operate similarly to the slider  8204 . For example, the slider  8304  may be slid away from the opening  8306  to increase the size of the opening  8306  and allow the tag  300  to be positioned in the opening  8306  ( FIG.  83 A ). The slider  8304  may then be slid towards the tag  300  to reduce the size of the opening  8306  and capture the tag  300  in the opening  8306  (e.g., by tightening the opening  8306  into the housing gap), as shown in  FIG.  83 B . The slider  8304  may use friction, ratchet mechanisms, clamps, cams, or other devices or techniques to prevent or limit unintended loosening. 
       FIG.  84 A  illustrates another example tag retainer  8400 . The tag retainer  8400  includes a body  8402  with two interconnected ratchet cords  8404 ,  8406  at least partially embedded in the body  8402 . The interconnected ratchet cords  8404 ,  8406  each include a ratchet mechanism  8408 ,  8410 , respectively. Thus, the ratchet cord  8404  may include the ratchet mechanism  8408 , and may extend through and engage with the ratchet mechanism  8410 . Similarly, the ratchet cord  8406  may include the ratchet mechanism  8410 , and may extend through and engage with the ratchet mechanism  8408 . The ratchet mechanisms  8408 ,  8410  may be configured to allow a corresponding ratchet cord to move therethrough in one direction, but restrain motion in another direction (similar to the operation of a zip tie). This ratcheting operation may be exploited to allow the tag retainer  8400  to be tightened by pulling on opposite sides of the tag retainer  8400 , as indicated by arrows  8412 . This force may cause both ratchet cords  8404 ,  8406  to tighten around the tag  300 , and the ratchet mechanisms  8408 ,  8410  lock the cords into the tightened state. 
     The ratchet cords  8404 ,  8406  may be semi-permanently retained in the tightened position by the ratchet mechanisms  8408 ,  8410 , such that they cannot be decoupled without damaging the ratchet mechanisms  8408 ,  8410 , the tag  300 , and/or some other portion of the tag retainer  8400 . In other cases, the ratchet mechanisms  8408 ,  8410  may be selectively releasable, such that a user can release the ratchet mechanisms  8408 ,  8410  with a button, latch, lever, or other mechanism and detach the tag  300  from the tag retainer  8400 . The ratchet cords  8404 ,  8406  may be formed from a polymer, metal, or any other suitable material, and may be at least partially embedded in the material of the body  8402  (which may be a polymer such as TPU, silicone, etc.). 
       FIG.  84 B  illustrates another example tag retainer  8420  that uses a ratchet mechanism to attach the tag retainer  8420  to the tag  300 . Whereas the tag retainer  8400  included two ratchet cords, the tag retainer  8420  includes a single ratchet cord  8422  that is looped about a portion of the tag  300 . For example, the ratchet cord  8422  may fit at least partially in and/or engage a housing gap of a tag, and a ratchet mechanism  8424  may releasably secure the ratchet cord  8422  in a closed, tightly looped configuration that retains the ratchet cord  8422  to the tag  300 . The ratchet cord  8422  may be tightened by pulling the ratchet cord  8422  along the direction  8426  while holding the tag  300  stationary. Releasing the ratchet cord  8422  may be achieved by actuating a button, latch, lever, or other mechanism of the ratchet mechanism  8424 , by using a tool, or by any other suitable manipulation of the ratchet cord  8422  or ratchet mechanism  8424 . The ratchet cord  8422  may be formed from a polymer, metal, or any other suitable material, and may be at least partially embedded in another material (which may be a polymer such as TPU, silicone, etc.). 
       FIGS.  85 A- 91 B  illustrate various example spring members for attaching to wirelessly locatable tags. These spring members all attach to a tag in a similar manner, namely by engaging the housing gap with a biasing force that maintains the tag retainer in the housing gap (and thus engaged with the undercuts and/or flanges defined by the housing gap). The spring members in  FIGS.  85 A- 91 B  may be used to attach directly to tags. When used to attach directly to tags, the spring members may be configured to attach to straps, cords, cables, ropes, clips, or other components so that the tag can be attached to something else (e.g., keys, a purse, luggage, a backpack, etc.). The spring members in  FIGS.  85 A- 91 B  may also be used as the spring members inside the bodies of other tag retainers. For example, the spring member  7404  in the tag retainer  7400  ( FIG.  74 A ) may be replaced with any of the spring members in  FIGS.  85 A- 91 B . 
       FIG.  85 A  shows an example spring member  8500  engaged with the tag  300  (e.g., secured in the housing gap). The spring member  8500  defines engagement regions  8504 , which are biased into the housing gap to attach the spring member  8500  to the tag  300 , and manipulation regions  8502 . The spring member  8500  may be formed from a round (in cross-section) wire formed from metal (e.g., spring steel, stainless steel, etc.), a polymer material, or the like. 
     The manipulation regions  8502  (also referred to herein as manipulators) are portions of the spring member  8500  that when pressed, pulled, or otherwise manipulated, allows the spring member  8500  to be easily decoupled from the tag  300 . For example, as shown in  FIG.  85 B , when opposing forces  8506  are applied to the manipulators  8502  (such as when a user pinches or squeezes the spring member  8500 ), the engagement regions  8504  spread out to define or increase a gap  8508  between the tag  300  and the engagement regions  8504 . This increased gap may be sufficiently large that the flange or lip of the battery door of the tag  300  can pass through the opening defined by the spring member  8500  to allow the tag  300  to be attached to and/or detached from the spring member  8500 . 
       FIG.  86 A  shows another example spring member  8600  engaged with the tag  300  (e.g., secured in the housing gap). The spring member  8600  defines engagement regions  8604 , which are biased into the housing gap to attach the spring member  8600  to the tag  300 , and manipulation regions  8602 . The spring member  8600  operates similar to the spring member  8500 . For example, forces  8606  applied to the manipulation regions  8602  cause the spring member  8600  to deform and define a gap  8608  ( FIG.  86 B ) that allows the tag  300  to be attached and/or detached. 
     Whereas the spring member  8500  may be formed from a circular wire (in cross-section), the spring member  8600  may be formed from a wire or ribbon with an elongated (e.g., rectangular) cross-sectional shape. The non-circular cross-sectional shape may be exploited to provide advantageous physical and/or mechanical properties to the spring member  8600 . For example, the spring member  8600  may be configured so the wider dimension is parallel with the radial dimension of the spring member  8600 . This orientation may provide a greater stiffness or resistance to deformation in the engagement regions  8604  as compared to the manipulation regions  8602 . The manipulation regions  8602 , on the other hand, may have the cross-section rotated by about 90 degrees, thus allowing the forces  8606  to deform the manipulation regions  8602  while limiting deformation of the engagement regions  8604 .  FIGS.  86 C and  86 D  are partial cross-sectional views of the spring member  8600 , viewed along lines  86 C- 86 C and  86 D- 86 D, respectively, in  FIG.  86 A .  FIGS.  86 C and  86 D  illustrate the orientations of the cross-sectional shape of the spring member  8600  at the engagement regions  8604  and manipulation regions  8602 , respectively. The spring member  8600  may be formed from an elongate (in cross-section) ribbon formed from metal (e.g., spring steel, stainless steel, etc.), a polymer material, or the like. The elongate ribbon may have a substantially rectangular cross-section. 
       FIGS.  87 A- 87 C  show another example spring member  8700  engaged with the tag  300  (e.g., secured in the housing gap). The spring member  8700  defines engagement regions  8704 , at least portions of which are biased into the housing gap to attach the spring member  8700  to the tag  300 , and manipulation regions  8702 . The spring member  8700  operates similar to the spring member  8500 . For example, forces  8706  applied to the manipulation regions  8702  cause the spring member  8700  to deform and define a gap  8708  ( FIG.  87 B ) that allows the tag  300  to be attached and/or detached. 
     The manipulation regions  8702  may define coiled springs, as shown in  FIG.  87 C . The coiled springs may provide the biasing force to maintain the engagement regions  8704  in engagement with the housing gap, while also defining manipulators  8702  that effectively direct forces to expand the engagement regions  8704 . The coiled springs may require relatively less actuation force than a spring member of similar cross-sectional shape but without the coiled springs. 
       FIGS.  88 A- 88 B  show another example spring member  8800  engaged with the tag  300  (e.g., secured in the housing gap). The spring member  8800  defines engagement regions  8804 , at least portions of which are biased into the housing gap to attach the spring member  8800  to the tag  300 , and manipulation regions  8802 . The spring member  8800  defines a hexagonal shape, with the engagement regions  8804  each defined by at least part of two respective sides (and the apex between those sides). The spring member  8800  operates similar to the spring member  8500 . For example, forces  8806  applied to the manipulation regions  8802  cause the spring member  8800  to deform and define a gap  8808  ( FIG.  88 B ) that allows the tag  300  to be attached and/or detached. 
       FIGS.  89 A- 89 B  show another example spring member  8900  engaged with the tag  300  (e.g., secured in the housing gap). The spring member  8900  defines engagement regions  8904 , at least portions of which are biased into the housing gap to attach the spring member  8900  to the tag  300 , and manipulation regions  8902 . The spring member  8900  defines an oblong shape, with the engagement regions  8904  each defined by a respective curved region having a first radius, and the manipulation regions  8902  each defined by a respective curved region having a second radius that is smaller than the first radius. The spring member  8900  operates similar to the spring member  8500 . For example, forces  8906  applied to the manipulation regions  8902  cause the spring member  8900  to deform and define a gap  8908  ( FIG.  89 B ) that allows the tag  300  to be attached and/or detached. 
       FIGS.  90 A- 90 B  show another example spring member  9000  engaged with the tag  300  (e.g., secured in the housing gap). The spring member  9000  defines engagement regions  9004 , at least portions of which are biased into the housing gap to attach the spring member  9000  to the tag  300 , and first and second manipulation regions  9002 ,  9003 . The manipulation regions  9002 ,  9003  have different shapes and may be positioned differently with respect to the tag  300  when the spring member  9000  is attached to the tag  300 . For example, when the spring member  9000  is attached to the tag, the first manipulation region  9002  extends beyond the housing gap (e.g., it is proud of the housing gap and defines a loop where straps, cords, cables, strings, or other components may be attached to couple the spring member  9000  to another object). The second manipulation region  9003 , by contrast, may remain within the housing gap (e.g., the second manipulation region  9003  may not extend past the flanges, lips, overhangs, or the like, that define the housing gap). In some cases, the second manipulation region  9003  may act as another engagement region, and may contact the tag  300  within the housing gap, when the spring member  9000  is not being attached to and/or detached from the tag  300 . 
     The spring member  9000  operates similar to the spring member  8500 . For example, forces  9006  applied to the first and second manipulation regions  9002 ,  9003  cause the spring member  9000  to deform and define a gap  9008  ( FIG.  90 B ) that allows the tag  300  to be attached and/or detached. Because the second manipulation region  9003  may be within the housing gap, the user may apply the opposing forces  9006  in various ways. As a first example, the user may press a fingernail, a coin, an edge of a credit card, a small tool, or some other implement against the second manipulation region  9003  (within the housing gap) while pushing the first manipulation region  9002  with a finger. This may allow the application of the opposing forces  9006  that expand the opening of the spring member  9000  and create the gap  9008 . As another example, a user may first apply a force  9006  to the first manipulation region  9002 , which may partially deform the spring member  9000  and force the second manipulation region  9003  out of the housing gap, at which time it will be accessible to a user to press against to more fully deform the spring member  9000  to produce the gap  9008  and allow the tag  300  to be attached and/or detached. 
       FIGS.  91 A- 91 B  show another example spring member  9100  engaged with the tag  300  (e.g., secured in the housing gap). The spring member  9100  defines engagement regions  9104 , at least portions of which are biased into the housing gap to attach the spring member  9100  to the tag  300 , and first and second manipulation regions  9102 ,  9103 . The overall shape of the spring member  9100  may be similar to that of the spring member  9000 , except that the second manipulation region  9103  may include a tab-like protrusion that extends beyond the housing gap such that a user can contact the second manipulation region  9103  without having to extend a tool or object into the housing gap (and without having to first deform the spring member  9100  by applying a force to the first manipulation region  9102 ). The tab-like protrusion of the second manipulation region  9103  may be integral with the remainder of the spring member  9100 . For example, the spring member  9100  may be formed from a single (e.g., monolithic) metal structure. In other implementations, the tab-like protrusion may be a separate component that is attached to or otherwise integrated with the remainder of the spring member  9100 . 
     In order to deform the spring member  9100  so that a tag  300  can be attached and/or detached, forces  9106  applied to the first and second manipulation regions  9102 ,  9103  cause the spring member  9100  to deform and define a gap  9108  ( FIG.  91 B ) that allows the tag  300  to be attached and/or detached. The tab-like protrusion of the second manipulation region  9103  may be sufficiently stiff to transmit the force  9106  to the remainder of the spring member  9100  without breaking or otherwise bending in a manner that would prevent or negatively affect the transfer of force to the remainder of the spring member  9100 . 
     The spring members shown and described with respect to  FIGS.  85 A- 91 B  may be formed in any suitable manner. For example, they may be formed by shaping (e.g., bending) metal wires or rods into the configurations shown. In such cases, the free ends of the metal used to form a spring member may be affixed to one another (e.g., by welding, brazing, adhesives, mechanical fasteners, etc.), or they may remain un-affixed (e.g., a seam or gap may remain between the free ends). As other examples, the spring members may be cast or molded. Where the spring members are formed from polymer materials and/or composites, they may be molded (e.g., injection molded), formed via additive manufacturing processes (e.g., 3D printing), or via any other suitable technique. Other methods of forming the spring members and other materials and/or combinations of materials are also contemplated. 
     As noted above, the spring members shown and described with respect to  FIGS.  85 A- 91 B  may be used as stand-alone components to help couple wirelessly locatable tags to other objects, or they may be integrated with other components of tag retainers. In the former cases, users may, for example, put clips, split rings (e.g., key rings), ropes, zip ties, or other components through or around the loops or other accessible areas of the spring members. In the latter cases, the spring members may be provided inside the bodies of other tag retainers, or may include carrying straps attached thereto.  FIGS.  92 A- 93    depict two example tag retainers that may use spring members such as those shown and described with respect to  FIGS.  85 A- 91 B . 
       FIG.  92 A  illustrates a portion of a tag retainer  9200  (which may be similar to the tag retainer  7400  in  FIG.  74 A ). The tag retainer  9200  includes the spring member  8500  ( FIG.  85 A ) at least partially embedded in a body  9202 . The body  9202  may be a polymer (e.g., TPU, silicone), a cloth or fabric, leather, or any other suitable material or combination of materials. The spring member  8500  may provide the biasing force that retains the portion of the body  9202  that defines the opening  9204  in a housing gap when the tag retainer  9200  is attached to a tag. The body  9202  may define or be coupled to a strap  9206 , which, as described above, may be any suitable type of strap or member that can be used to attach the tag retainer  9200  to another object. 
       FIG.  92 B  is a partial cross-sectional view of the tag retainer  9200  of  FIG.  92 A , viewed along line  92 B- 92 B in  FIG.  92 A .  FIG.  92 B  illustrates how the spring member  8500  may be embedded in the material of the body  9202 . In this case, the body  9202  may be a polymer material that is molded around the spring member  8500  (which may be inserted into a mold prior to the polymer material being injected). 
       FIG.  93    illustrates a portion of a tag retainer  9300  that includes the spring member  9000  ( FIG.  90 A ) and a strap member  9302  attached to the manipulation region  9002  of the spring member  9000 . The strap member  9302  may be attached to the spring member  9000  in any suitable way. As one example, it may be attached via insert molding in which the strap member  9302  encapsulates a portion of the spring member  9000 . Alternatively, it may be attached using stitches (e.g., sewn), snaps, buttons, staples, glue, hook-and-loop fasteners, or the like. 
       FIGS.  94 A- 94 B  illustrate another example tag retainer  9400  for attaching to a tag. The tag retainer  9400  may include a body  9402 , which may be formed from or include a polymer material or other compliant material (including combinations of materials), and a spring member  9404 , which may be formed from a material with a greater stiffness than the body (e.g., spring steel, a polymer, etc.). The spring member  9404  may be configured to bias the body  9402  into the housing gap of a tag, as described with respect to other spring members. The spring member  9404  and the body  9402  may cooperate to define a pull tab  9406  that is used to help expand the opening of the tag retainer  9400  to facilitate attachment and detachment of the tag  300 , as described with respect to  FIG.  94 B . The spring member  9404  may define engagement ends  9405  that are separated by a gap  9408 . 
     The body  9402  and the spring member  9404  may be configured to help prevent accidental detachment of the tag  300  from the tag retainer  9400 . For example, when a force  9410  is applied to the tag  300  while the tag  300  is attached to the tag retainer  9400 , the force may be transferred through the tag retainer to the object to which it is connected (as represented by arrow  9412 ). The force  9410  may correspond to the tag  300  snagging or catching on another object, such as may occur during normal everyday use of the tag retainer  9400 . Because the force  9410  is being applied to the tag retainer  9400  through the tag  300  (at interface  9411 ), the opening in the body  9402  resists expansion and thus helps retain the tag  300  in place despite the force. 
     On the other hand, the tag  300  may be attached to and detached from the tag retainer  9400  by applying a force to the pull tab  9406 .  FIG.  94 B  illustrates the tag retainer  9400  when a force  9414  is applied to the pull tab  9406  (and an opposite side of the tag retainer  9400 ). Because the force is applied to the pull tab  9406 , the tag  300  engages the engagement ends  9405  of the spring member  9404  resulting in the gap  9408  expanding and a gap  9416  being produced proximate the pull tab  9406 . This gap  9416  facilitates removal of the tag  300  from the tag retainer  9400 . Because applying a force to the pull tab  9406  requires a more deliberate and purposeful action by a user (as compared, for example, to a tag  300  becoming snagged on a passing object), the tag retainer  9400  helps keep the tag  300  attached during normal use, while providing an easy and straightforward way to attach and detach the tag  300  when desired. 
       FIGS.  95 A- 95 B  illustrate another example tag retainer  9500  for attaching to a tag. The tag retainer  9500  may include a body  9502 , which may be formed from or include a polymer material or other compliant material (including combinations of materials), and spring members  9504 ,  9506 , which may be formed from a material with a greater stiffness than the body (e.g., spring steel, a polymer, etc.). The spring members  9504 ,  9506  may be configured to bias the body  9502  into the housing gap of a tag, as described with respect to other spring members. The spring members  9504 ,  9506  may have semi-circular shapes and may be positioned on opposite sides of the opening in the body  9502 . The spring members  9504 ,  9506  may also increase the stiffness of portions of the tag retainer  9500  that extend into the housing gap, thereby decreasing the likelihood that the tag  300  will simply deform or fold the body  9502  out of the way and allow the tag  300  to unexpectedly detach from the tag retainer  9500 . 
     The body  9502  may define a pull tab  9508 . The pull tab  9508  may lack any spring members. As shown in  FIG.  95 B , a user may grasp the pull tab  9508  to apply a force  9510  to the pull tab  9508 , thereby deforming the body  9502  (and optionally one or both of the spring members  9504 ,  9506 ) and introducing or increasing the size of a gap  9512  between the tag  300  and the body  9502 , thereby facilitating attachment or detachment of the tag  300 . 
       FIGS.  96 A- 96 B  illustrate another example tag retainer  9600  for attaching to a tag. The tag retainer  9600  may include a body  9602 , which may be formed from or include a polymer material or other compliant material (including combinations of materials), and a spring member  9604  which may be formed from a material with a greater stiffness than the body (e.g., spring steel, a polymer, etc.). The spring member  9604  may be configured to bias the body  9602  into the housing gap of a tag, as described with respect to other spring members. 
     The spring member  9604  may define two spring arms  9606  that can be selectively secured together (or released) using a clip mechanism  9608 .  FIG.  96 A  shows the tag retainer  9600  with the clip mechanism  9608  in a closed configuration in which the spring arms  9606  are secured together. This may retain the tag retainer  9600  in a tightened or secure state in which the tag  300  is securely attached to the tag retainer  9600 .  FIG.  96 B  shows the tag retainer  9600  with the clip mechanism  9608  in an open configuration. When the clip mechanism  9608  is open, the spring member  9604  returns to a relaxed state in which the spring arms  9606  pull away from one another, thereby generally expanding the spring member  9604  and expanding the opening in which the tag  300  is received. This expansion facilitates the attachment and/or detachment of the tag retainer  9600  and the tag  300 . The clip mechanism  9608  may be opened, for example, by rotating or twisting the clip mechanism  9608  (or a portion or component of the clip mechanism  9608 ), as illustrated by arrow  9605 . Other types and/or configurations of clip mechanisms may be opened and/or closed using other types of manipulations. 
       FIG.  97    illustrates another example tag retainer  9700  for attaching to a tag. The tag retainer  9700  may include a body  9702 , which may be formed from or include a polymer material or other compliant material (including combinations of materials), and a spring member  9704  which may be formed from a material with a greater stiffness than the body (e.g., spring steel, a polymer, etc.). The spring member  9704  may be configured to bias the body  9702  into the housing gap of a tag, as described with respect to other spring members. The spring member  9704  may have an octagonal shape with eight substantially linear sides, which each extend into the housing gap of the tag  300  to help retain the tag  300  to the tag retainer  9700 . In some cases, the spring member  9704  may define uncoupled ends to allow the spring member  9704  to expand in order to facilitate attachment and detachment of the tag  300 . In some cases, the ends of the spring member  9704  are connected (e.g., welded), and the spring member  9704  deforms (e.g., one or more of the straight sides deflects) during attachment and/or detachment of the tag  300 . 
       FIGS.  98 A- 98 B  illustrate another example tag retainer  9800  for attaching to a tag. The tag retainer  9800  may include a body  9802 , which may be formed from or include a polymer material or other compliant material (including combinations of materials), and a spring member  9804  which may be formed from a material with a greater stiffness than the body  9802  (e.g., spring steel, a polymer, etc.). The spring member  9804  may be configured to bias the body  9802  into the housing gap of a tag, as described with respect to other spring members. The tag retainer  9800  may also include a stiffener  9810  along a portion of the opening for the tag, which may help maintain the shape of the tag retainer  9800  during manipulations of the spring member  9804  (for attaching/detaching the tag  300 ) and may provide additional stiffness to the portion of the body  9802  that extends into the housing gap. 
     The spring member  9804  may define engagement regions  9805  and an actuation region  9806 . The engagement regions  9805  may be biased towards the tag  300  and engage the tag  300  in the housing gap. The actuation region  9806  may be defined by a curved portion of the spring member  9804 , and may include or be coupled to a manipulation tab  9808  (which may be integral with the spring member  9804  or may be a separate component that is attached to the spring member  9804 ). The manipulation tab  9808  may be exposed or otherwise accessible to a user, and may be used to apply a force to the actuation region  9806  to expand the spring member  9804  to facilitate attachment and detachment of the tag  300 . For example, the undeformed or unstressed configuration of the spring member  9804  may be shown in  FIG.  98 A . In this configuration, the spring member  9804  is biased into engagement with the tag  300  (e.g., in the housing gap) and retains the tag  300  to the tag retainer  9800 . In order to conveniently attach or detach the tag  300 , a user may grasp the manipulation tab  9808  and apply a force away from the tag  300  (while optionally grasping the tag  300 ). The force, represented by arrow  9812  in  FIG.  98 B , deforms the spring member  9804 , including by pulling the engagement regions  9805  (and the nearby portions of the body  9802 ) away from the tag  300  and producing a gap  9814  that facilitates attachment and detachment of the tag  300 . 
       FIGS.  99 A- 99 C  illustrate an example tag cover  9900  for attaching to a tag. The tag cover  9900  may be configured to protect the tag from impacts, scratches, or other damage. The tag cover  9900  may also change the size and/or friction characteristics of the tag  300 . For example, the tag cover  9900  may have a higher coefficient of friction than the tag itself, and may make the tag  300  easier to handle, less likely to slip out of the user&#39;s hand, or the like. 
     The tag cover  9900  may include an engagement flange  9904  that defines a first opening, and a sidewall  9906  that defines a second opening. The engagement flange  9904  may be configured to extend into a housing gap of the tag  300 , as shown in  FIGS.  99 B and  99 C  (which are partial cross-sectional views of the tag and tag cover of  FIG.  99 A , viewed along line  99 B- 99 B in  FIG.  99 A ). The sidewall  9906  may have two stable configurations when the tag cover  9900  is attached to the tag  300  (e.g., it may be bistable).  FIG.  99 B  shows the tag cover  9900  in a first configuration, where the sidewall  9906  is extended upward, away from the tag  300 . This configuration may facilitate attachment and detachment of the tag cover  9900 , as the sidewall may be moved out of the way of the engagement flange  9904  so that the engagement flange  9904  can be inserted into or removed from the housing gap of the tag  300 .  FIG.  99 C  shows the tag cover  9900  in a second configuration, where the sidewall  9906  is positioned against the tag  300 . This configuration may correspond to the normal use configuration of the tag cover  9900 , as the sidewall  9906  is at least partially covering, and optionally in direct contact with, the outer peripheral side of the tag  300 . 
       FIGS.  100 A- 100 D  illustrate another example tag retainer  10010  ( FIG.  100 B ) for attaching to a tag  10000  ( FIG.  100 A ). The tag  10000  and tag retainer  10010  may include complementary mating features that allow the tag retainer  10010  to securely attach to the tag  10000 . In particular, with reference to  FIG.  100 A , the tag  10000  may include a battery door  10001  (similar to the bottom housing member  304 , or battery door, of the tag  300  in  FIG.  3   ) that defines engagement features  10002 . The engagement features  10002  may each define undercut slots  10004 , which may be open on one end and blocked at the opposite end. 
     With reference to  FIG.  100 B , the tag retainer  10010  may include a body, which may be formed from or include a polymer material or other compliant material (including combinations of materials). The corresponding engagement features  10012  may be formed from a material with a greater stiffness than the body (e.g., spring steel, a polymer, etc.). The tag retainer  10010  defines an opening  10011  that is configured to receive at least part of the tag  10000  therein, and corresponding engagement features  10012  that are complementary to the engagement features  10002  of the tag  10000 . The corresponding engagement features  10012  may be tabs, clips, flanges, protrusions, or other suitable features. In the illustrated example, the engagement features  10002  of the tag  10000  define slots, and the corresponding engagement features  10012  define tabs with a shape and size to be received in the slots, though this is merely one example set of complementary engagement features, and others are also contemplated. 
       FIG.  100 C  illustrates the tag retainer  10010  being attached to the tag  10000 . The tag retainer  10010  is positioned so that the corresponding engagement features  10012  are positioned between the engagement features  10002  of the tag  10000 , thereby aligning the corresponding engagement features  10012  with the slots defined by the engagement features  10002 . The tag retainer  10010  is rotated, as illustrated by arrow  10014 , to slide the corresponding engagement features  10012  into the engagement features  10002 . Once the engagement features  10002 ,  10012  are engaged, the tag retainer  10010  is attached to the tag  10000 , as shown in  FIG.  100 D . 
     The engagement features  10002 ,  10012  may include clips, latches, detents, undercuts, and/or other features that help maintain the features  10002 ,  10012  in secure engagement. Such features may, for example, require a greater force to initially disengage the engagement features  10002 ,  10012 , followed by a lower force requirement to fully slide the engagement features  10002 ,  10012  completely apart. 
       FIGS.  101 A- 101 C  illustrate another example tag retainer  10100  for attaching to a tag. The tag retainer  10100  may include a body  10102 , which may define an opening  10104 . The body  10102  may be formed from or include a polymer material or other compliant material (including combinations of materials), and may include other components or materials such as spring members, stiffeners, etc. The opening  10104  may be an opening to a partially enclosed pocket that receives a portion of a tag. 
       FIG.  101 B  is a partial cross-sectional view of the tag retainer  10100  of  FIG.  101 A , viewed along line  101 B- 101 B in  FIG.  101 A . The opening  10104  may be defined by a wall (e.g., a circular wall)  10106  that is configured to engage a tag via a housing gap. 
       FIG.  101 C  is another partial cross-sectional view of the tag retainer  10100  of  FIG.  101 A , viewed along line  101 B- 101 B in  FIG.  101 A , showing the tag retainer  10100  attached to the tag  300 . As shown, the partially enclosed pocket has a size (e.g., a diameter, volume, etc.) that is substantially equal to the outer part of the battery door of the tag  300 , and the battery door is substantially contained and/or enclosed in the pocket. The wall  10106  extends into the housing gap of the tag  300  to retain the tag  300  to the tag retainer  10100 . The stiffness of the material of the wall  10106  (including any stiffeners within or attached to the body  10102 ) may bias the wall  10106  into the housing gap to provide a secure attachment. 
     By attaching to the battery door, the main body portion  302  of the tag  300  is exposed and uncovered. As the main body portion  302 , and more particularly the top housing member of the tag, may define a diaphragm-like member to produce audio outputs, attaching the tag retainer  10100  to the tag  300  in a manner that exposes the top housing member may help avoid degrading or muting the audio output. 
     While  FIGS.  101 A- 101 C  illustrate a tag retainer that attaches to a battery door of a tag,  FIG.  101 D  illustrates an example tag retainer that attaches to the tag  300  in place of the battery door  304 .  FIG.  101 D  illustrates the tag  300  with the bottom housing member or battery door  304  removed from the main body portion  302 . A tag retainer  10110  may include or define a strap  10112  or attachment portion that is used to attach the tag retainer  10110  to another object. 
     The tag retainer  10110  may also include a flange  10114  and latching members  10116 . The flange  10114  may resemble a similar structure of the battery door  304 , and the latching members  10116  may have substantially the same size, shape, and overall configuration of the latching members of the battery door  304 . The latching members  10116  may be configured to engage the tag  300  in the same or similar manner to the latching members of the battery door  304 . In this manner, the main body portion  302  may be interchangeably attached to the battery door  304  or the tag retainer  10110  using the same engagement features of the main body portion  302 . 
       FIGS.  102 A- 102 C  illustrate another example tag retainer  10200  for attaching to a tag. The tag retainer  10200  may include a body  10202 , which may define an opening  10204 . The body  10202  may be formed from or include a polymer material or other compliant material (including combinations of materials), and may include other components or materials such as spring members, stiffeners, etc. The opening  10204  may be an opening to a partially enclosed pocket that receives a portion of a tag. 
       FIG.  102 B  is a partial cross-sectional view of the tag retainer  10200  of  FIG.  102 A , viewed along line  102 B- 102 B in  FIG.  102 A . The opening  10204  may be defined by a wall (e.g., a circular wall)  10206  that is configured to engage a tag via a housing gap. 
       FIG.  102 C  is another partial cross-sectional view of the tag retainer  10200  of  FIG.  102 A , viewed along line  102 B- 102 B in  FIG.  102 A , showing the tag retainer  10200  attached to the tag  300 . Whereas the tag retainer  10100  is configured to attach to the tag  300  via the battery door, the tag retainer  10200  is configured to attach to the tag  300  by wrapping around the main body portion  302  of the tag  300 . Thus, the partially enclosed pocket has a size (e.g., a diameter, volume, etc.) that is substantially equal to the outer part of the main body portion  302  of the tag  300 , and the outer part of the main body portion  302  is substantially contained and/or enclosed in the pocket. The wall  10206  may extend into the housing gap of the tag  300  to retain the tag  300  to the tag retainer  10200 . The stiffness of the material of the wall  10206  (including any stiffeners within or attached to the body  10202 ) may bias the wall  10206  into the housing gap to provide a secure attachment. In other cases, the wall  10206  does not extend into the housing gap, but instead securely attaches to the tag  300  due to the wall  10206  extending over a portion of the tag  300  and trapping the tag  300  in the pocket of the tag retainer  10200 . 
       FIGS.  103 A- 103 B  illustrate another example tag  10300  with a configuration for facilitating attachment to and detachment from a tag retainer. In particular, the tag  10300  includes a main body portion  10302  (similar to the main body portion  302  of the tag  300 ) and a battery door  10304  (similar to the bottom housing member  304 , or battery door, of the tag  300 ). The battery door  10304  is configured to slide, translate, or otherwise move relative to the main body portion  10302 . For example,  FIG.  103 A  illustrates the tag  10300  with the battery door  10304  in an undeflected position relative to the main body portion  10302 . In this position, the battery door  10304  may be substantially centered over a shaft  10306  of the main body portion  10302 . Accordingly, the battery door  10304  may overhang the shaft  10306  to define the housing gap of the tag  10300 .  FIG.  103 B  illustrates the tag  10300  with the battery door  10304  in a deflected position. In this position, at least one side of the battery door  10304  may be substantially flush with a side of the shaft  10306 . The battery door  10304  may slide, translate, or otherwise move only a fixed distance relative to the main body portion  10302 , and may use any suitable mechanism to facilitate the motion (e.g., friction guides, bearings, bushings, etc.). Further, while the battery door  10304  and the shaft  10306  are shown as having circular shapes, other shapes are also contemplated, including oblong shapes, ovals, rectangles, ellipses, or the like. 
       FIGS.  104 A- 104 D  illustrate steps of an example process for attaching the tag  10300  to a tag retainer  10400  (which may resemble the tag retainer  7600 ,  FIG.  76 A , or other tag retainers described herein). The tag retainer  10400  may be less compliant than other tag retainers, as the movement of the battery door  10304  can facilitate attachment and detachment while reducing the need for the tag retainer  10400  to deflect or deform. 
     As shown in  FIG.  104 A , the tag retainer  10400  may be engaged with the tag  10300  at a first location  10404  while the battery door  10304  is in an undeflected position. After engaging at the location  10404 , the user may slide the battery door  10304  into a deflected position (arrow  10401 ), which reduces the overhang of the battery door  10304  relative to the shaft  10306  at a second location  10406 . This allows the tag retainer  10400  to more easily slide over the battery door  10304  and into the housing gap, as indicated by arrow  10402 .  FIG.  104 B  shows the tag retainer  10400  in place in the housing gap. Sliding the battery door  10304  back towards the undeflected position (arrow  10408 ,  FIG.  104 C ) captures the tag retainer  10400  in the housing gap and retains the tag retainer  10400  to the tag  10300  (as shown in  FIG.  104 D ). 
       FIGS.  105 A- 105 D  illustrate another example tag  10500  with a configuration for facilitating attachment to and detachment from a tag retainer. In particular, the tag  10500  includes a main body portion  10502  (similar to the main body portion  302  of the tag  300 ), and a battery door  10504  that includes a bistable retraction mechanism that can be actuated to form (or remove) a housing gap.  FIG.  105 A  shows the battery door  10504  in an extended configuration. In this configuration, the battery door  10504  does not define an undercut or lip, and thus does not define a housing gap. Rather, the extended battery door  10504  has substantially straight sides such that a tag retainer can be slid over the extended battery door  10504  without requiring the tag retainer to deform or deflect.  FIG.  105 B  shows the battery door  10504  in a retracted configuration. In this configuration, the battery door  10504  is compressed to define a housing gap  10505  that can trap a tag retainer therein. 
     The battery door  10504  may include a bistable retraction mechanism and a compliant cover. The bistable retraction mechanism may operate similar to a retractable pen. For example, pressing the battery door  10504  when the bistable retraction mechanism is retracted ( FIG.  105 B ) will result in the bistable retraction mechanism extending ( FIG.  105 A ), and vice versa. The compliant cover may enclose internal components of the bistable retraction mechanism, such as cams, arms, plates, springs, and the like. The compliant cover may be a fabric, polymer (e.g., silicone, TPU, etc.), leather, mechanically linked rigid plates, or the like. 
       FIGS.  105 C- 105 D  illustrate how the tag  10500  may be attached to a tag retainer  10506 . As shown in  FIG.  105 A , the battery door  10504  may be extended so that the opening of the tag retainer  10506  may be passed over the extended battery door  10504  to rest against a surface of the tag  10500  (e.g., the main body portion  10502 ). Once the tag retainer  10506  is in place, a force may be applied to the battery door  10504 , as illustrated by arrow  10508 , to force the battery door  10504  into a retracted position.  FIG.  105 D  shows the battery door  10504  in the retracted configuration, with the tag retainer  10506  captured in the housing gap  10505  (e.g., between the battery door  10504  and the main body portion  10502 ). Detaching the tag retainer  10506  from the tag  10500  may be accomplished by reversing these operations. 
       FIGS.  106 A- 106 B  illustrate another technique for attaching the tag  300  to a tag retainer  10600 . The tag retainer  10600  defines an opening  10602  that is configured to receive a portion of the tag  300 . More particularly, the battery door  304  of the tag  300  is separated from the main body portion  302 , and the tag retainer  10600  is positioned between the battery door  304  and the main body portion  302  such that a portion of the tag  300  is in the opening  10602  and such that a portion of the tag retainer  10600  is captured between the battery door  304  and the main body portion  302  (e.g., in the housing gap of the tag  300 ).  FIG.  106 A  shows an exploded view of the tag  300  in position to be attached to the retainer  10600 , and  FIG.  106 B  shows the tag  300  attached to the tag retainer  10600 , with the battery door  304  attached to the main body portion  302  and the tag retainer  10600  captured in the housing gap. The tag retainer  10600  may be any suitable tag retainer, such as those described herein. Because the tag retainer  10600  (and in particular the opening  10602 ) does not need to expand or deform to facilitate attachment to the tag, the tag retainer  10600  may be more rigid or stiff than other tag retainers described herein. This stiffness may be accomplished by forming the tag retainer  10600  from stiffer materials (e.g., polycarbonate, metals, ABS, etc.), or incorporating stiff materials in the tag retainer  10600 . For example, a closed-ring spring member, such as that shown in  FIGS.  76 A- 76 C , may be incorporated into the tag retainer  10600  around the opening  10602  and encapsulated by a compliant material that forms the rest of the tag retainer  10600 . In comparison to the tag retainer  7600 , however, the opening  10602  (and the diameter of the closed-ring spring member) may be smaller than the opening  7601  due to the fact that the opening  10602  does not need to fit over the battery door to attach the tag to the tag retainer. For example, the opening  10602  may have a diameter that is substantially the same size as the smallest-diameter surface of the housing gap, with only a small amount of clearance to allow for opening  10602  to accept the portion of the tag therein. 
       FIGS.  107 A- 107 B  illustrate another example tag  10700  with a configuration for facilitating attachment to and detachment from a tag retainer. In particular, the tag  10700  includes a main body portion  10702  (similar to the main body portion  302  of the tag  300 ), and a battery door that includes a bistable flange  10704  that can be manipulated to form (or remove) a housing gap.  FIG.  107 A  shows the bistable flange  10704  in an extended configuration. In this configuration, the bistable flange  10704  does not define an undercut or lip, and thus does not define a housing gap. Rather, the extended bistable flange  10704  has substantially straight sides such that a tag retainer can be slid over the extended bistable flange  10704  without requiring the tag retainer to deform or deflect.  FIG.  107 B  shows the bistable flange  10704  in a retracted configuration. In this configuration, the bistable flange  10704  has been forced into a retracted configuration to define a housing gap  10705  that can trap a tag retainer therein. 
       FIGS.  108 A- 108 B  illustrate how the tag  10700  may be attached to a tag retainer  10800 . As shown in  FIG.  108 A , the bistable flange  10704  may be extended so that the opening of the tag retainer  10800  may be passed over the extended bistable flange  10704  to rest against a surface of the tag  10700  (e.g., the main body portion  10702 ). Once the tag retainer  10800  is in place, a force may be applied to the bistable flange  10704 , as illustrated by arrows  10802 , to force the bistable flange  10704  into a retracted position.  FIG.  108 B  shows the bistable flange  10704  in the retracted configuration, with the tag retainer  10800  captured in the housing gap  10705  (e.g., between the bistable flange  10704  and the main body portion  10702 ). Detaching the tag retainer  10800  from the tag  10700  may be accomplished by reversing these operations. 
     The bistable flange  10704  may be formed from or include any suitable material. For example, the bistable flange  10704  may be formed from a polymer material such as a silicone, TPU, or the like. The bistable flange  10704  may be a single piece of material, or it may include multiple components. For example, the bistable flange  10704  may include an internal bistable member (e.g., a metal having a shape and/or material that produces a bistable configuration) with a compliant outer sheathing material (e.g., silicone, TPU, etc.). Other configurations are also contemplated. 
       FIGS.  109 A- 109 D  illustrate another example tag  10900  ( FIG.  109 A ), and corresponding tag retainer  10910  ( FIG.  109 B ) for attaching to the tag  10900 . With reference to  FIG.  109 A , the tag  10900  includes a main body portion  10902  (similar to the main body portion  302  of the tag  300 ), and a battery door  10904 . The tag  10900  may define channels  10906 , which may be formed in the battery door  10904 , that are configured to receive latch members  10916  of the tag retainer  10910  ( FIG.  109 B ). The channels  10906  may include or define ramp segments  10920 , which may be used to guide the latch members  10916  of a tag retainer out of the channels  10906  when decoupling the tag retainer  10910  from the tag  10900 . 
     The tag  10900  may also include optional magnetic components  10908  (e.g., magnets) that are configured to magnetically attract to the latch members  10916  to help draw the latch members  10916  into the channels  10906  and retain them in the channels  10906 . The tag  10900  may also include optional repelling magnetic components  10922  (e.g., magnets having an opposite polarity to the magnets  10908 ) that are configured to repel the latch members  10916  out of the channels  10906  when the tag retainer  10910  is rotated (such that the latch members  10916  slide along the ramp segments  10920 ). The combination of the ramp segments  10920  and the repelling magnetic components  10922  may provide an impetus that causes the latch members  10916  to retract back into a retracted position in the tag retainer  10910 . 
     The tag retainer  10910 , shown in  FIG.  109 B , includes a body  10912  (similar to the bodies of other tag retainers described herein) that defines an opening  10914  configured to receive at least a portion of the tag  10900  (e.g., the battery door  10904 ). The tag retainer  10910  may include latch members  10916  that can be retracted into and/or extended out from the tag retainer  10910  to engage the channels  10906  of the tag  10900 , as illustrated by arrows  10918 . The latch members  10916  may define ramped or contoured portions  10926  that facilitate a smooth engagement between the latch members  10916  and the ramp segments  10920  of the channels  10906  when the tag retainer  10910  is rotated (which causes the latch members  10916  to slide along the ramp segments  10920 ). 
     The latch members  10916  may be spring-loaded so that they are biased in an outward or protruding position, or they may be unbiased. In other cases, they are biased in a retracted position, and are drawn into the channels  10906  due to a magnetic attraction between the latch members  10916  and the magnetic components  10908  in the tag retainer  10910 . 
     The latch members  10916  may be formed or include magnetic materials (e.g., a ferromagnetic material, if the magnetic components  10908  are permanent magnets) to facilitate the latch members  10916  being pulled into and retained in the channels  10906 . The tag retainer  10910  may also include magnetic components  10924  (e.g., magnets) that are configured to bias the latch members  10916  into the body of the tag retainer  10910  or retain the latch members  10916  in the withdrawn or retracted position. The strength of the magnetic attraction between the latch members  10916  and the magnet components  10924  may be less than that of the attraction between the latch members  10916  and the magnetic components  10908  in the tag. In this way, the latch members  10916  may be securely retained in the channels  10906  by the magnetic components  10908  until the latch members  10916  are forced out of the channels  10906  (e.g., by the ramp segments  10920  and/or repelling magnetic components  10922 ), at which time the weaker magnetic attraction from the magnetic components  10924  may overcome the reduced magnetic attraction from the magnetic components  10908 , thereby drawing the latch members  10916  back into the tag retainer  10910  and retaining them in the retracted position. To attach the tag  10900  to the tag retainer  10910 , the tag retainer  19010  may be positioned so that the latch members  10916  are aligned with the channels  10906 . In this alignment, the magnetic attraction between the latch members  10916  and the magnetic components  10908  may overcome the attraction between the latch members  10916  and the magnetic components  10924 , thereby drawing the latch members  10916  into the channels to retain the tag  10900  to the tag retainer  10910 . 
       FIG.  109 C  shows the tag  10900  attached to the tag retainer  10910 . As shown, the latch members  10916  have extended into the channels  10906 , thereby attaching the tag  10900  to the tag retainer  10910 . Due to the optional spring biasing and/or the optional magnetic attraction, the latch members  10916  may be drawn into the channels  10906  as soon as the battery door  10904  is inserted into the opening  10914  of the tag retainer  10910  and the latch members  10916  are aligned with the channels  10906 . 
       FIG.  109 D  shows how the latch members  10916  may be retracted into the tag retainer  10910  to detach the tag  10900  from the tag retainer  10910 . For example, the tag retainer  10910  may be rotated relative to the tag  10900  (as indicated by arrow  10928  in  FIG.  109 C ), which causes the latch members  10916  to slide along and be ejected by the ramp segments  10920  (and optionally repelled by the repelling magnetic components  10922  and further retracted by the magnetic components  10924 ). 
       FIG.  110 A  illustrates another example tag  11000 . The tag  11000  includes a main body portion  11002  (similar to the main body portion  302  of the tag  300 ), and a battery door  11004 . The tag  11000  includes one or more accessory retention mechanisms  11006  integrated with the battery door  11004 . The accessory retention mechanisms  11006  may be configured to help retain the tag  11000  to an accessory such as a tag retainer. 
       FIG.  110 B  is a partial cross-sectional view of the tag  11000  of  FIG.  110 A , viewed along line  110 B- 110 B in  FIG.  110 A .  FIG.  110 B  shows an example configuration of the accessory retention mechanisms  11006 . In particular, the accessory retention mechanisms  11006  may include a plunger  11008  that is accessible to the user from the outer or exterior surface of the tag  11000 , and one or more spring members  11012  biasing the plunger  11008  upwards. The accessory retention mechanisms  11006  may be situated within (and captive in) an opening  11010  in the battery door  11004 , and the opening may be configured to receive therein a retention member of an accessory to help hold the accessory in place and attached to the tag  11000 . 
       FIGS.  111 A- 111 B  illustrate partial cross-sectional views of the tag  11000  in use with an accessory  11100 , which may be a tag retainer similar to others described herein. The accessory  11100  may include a retention member  11102  that is biased, by a spring member  11104 , in a proud or protruding configuration (relative to adjacent portions of the accessory  11100 ).  FIG.  111 B  shows the accessory  11100  attached to the tag  11000 . In this configuration, the retention member  11102  is extended into the opening  11010  such that the retention member  11102  engages the opening  11010  and retains the accessory  11100  to the tag  11000 . 
     In order to detach the accessory  11100  from the tag  11000 , a user may apply a force to the plunger  11008  of the accessory retention mechanism  11006  (indicated by arrow  11106 ,  FIG.  111 B ), thereby forcing the plunger  11008  against the retention member  11102  in a manner that overcomes the biasing force of the retention member  11102  and pushes the retention member  11102  out of the opening  11110 . In this configuration, as shown in  FIG.  111 B , the accessory  11100  may be easily slid out of the housing gap  11015  to detach the accessory  11100  from the tag  11000 . 
     The accessory  11100  may have an enclosed (e.g., circular) opening, similar to the tag retainer  7600 , for example. Because the accessory retention mechanisms  11006  can retain an accessory to the tag without the accessory fully encircling the housing gap, the accessory  11100  does not necessarily require a continuous opening. For example, the accessory  11100  may be a straight strap-like accessory with a free end that is narrower than the width (e.g., diameter) of the tag  11000  and that extends into the housing gap  11015  only at a location proximate the accessory retention mechanism  11006 . In some cases, an additional mechanism or retention feature is positioned on the tag  11000  on the opposite side of the accessory  11100  to retain the accessory  11100  from the underside as well. 
       FIG.  112 A  illustrates another example tag  11200 . The tag  11200  includes a main body portion  11202  (similar to the main body portion  302  of the tag  300 ), and a battery door  11204 . The tag  11200  includes an accessory biasing mechanism  11206  integrated with the tag  11200 . The accessory biasing mechanisms  11206  may be configured to help retain the tag  11200  to an accessory such as a tag retainer, and may help prevent the tag  11200  from moving (e.g., spinning, rattling) when attached to an accessory such as a tag retainer. The accessory biasing mechanism  11206  may be positioned in a housing gap  11210  ( FIG.  112 B ), and may be configured to push against an accessory that is engaged with the housing gap  11210 . The tag  11200  may include a spring member  11208  that biases the accessory biasing mechanism  11206  in a protruding configuration, as shown in  FIG.  112 B  (which is a partial cross-sectional view of the tag  11200  of  FIG.  112 A , viewed along line  112 B- 112 B in  FIG.  112 A ). 
       FIGS.  67 A- 67 B  illustrate the interaction of an accessory  11300  (which may be a tag retainer similar to the tag retainer  7600 , or other tag retainers described herein) with the tag  11200  and the accessory biasing mechanism  11206 . In particular, as the accessory  11300  is being attached to the tag  11200 , the accessory may engage the tag  11200  by entering the housing gap at one side  11302  of the tag. Force from the accessory pushing against the accessory biasing mechanism  11206  may result in deflection of the accessory biasing mechanism  11206  into a recess in the tag  11200  (and may result in the accessory biasing mechanism  11206  being flush with adjacent portions of the tag  11200 ). The accessory  11300  may then be engaged with a second side  11306  of the tag by extending the accessory  11300  over the battery door  11204  and into the housing gap (indicated by arrow  11304 ).  FIG.  113 B  shows the tag  11200  with the accessory  11300  attached and retained in the housing gap  11210 . The accessory biasing mechanism  11206 , forced outward by the spring member  11208 , applies a force to the accessory  11300 . This force may provide several advantages. For example, it may increase the engagement force between the accessory  11300  and the tag  11200  at the side opposite the accessory biasing mechanism  11206  (e.g., at the second side  11306 ). Further, it may increase the frictional force between the tag  11200  and the accessory  11300 , thereby preventing or limiting rotation, rattling, or other motion of the tag  11200  relative to the accessory  11300 . 
       FIG.  114 A  illustrates another example tag retainer  11400  that may be attached to a tag. The tag retainer  11400  may include a body  11402 , which may be formed from or include a polymer material or other compliant material (including combinations of materials). The tag retainer  11400  defines an opening  11404  for receiving a tag (e.g., the tag  300 ). The tag retainer  11400  may also include a latch member  11406  that extends into the opening  11404  and is biased outward by a spring member  11408 . The latch member  11406  may be configured to be forced against a tag (e.g., the housing gap of a tag) to help retain the tag to the tag retainer  11400 . 
       FIG.  114 B  is a partial cross-sectional view of the tag retainer  11400  of  FIG.  114 A , viewed along line  114 B- 114 B in  FIG.  114 A , showing the tag retainer  11400  attached to the tag  300 . As shown, the latch member  11406  is forced, by the spring member  11408 , against a surface of the tag  300  within the housing gap. The force from the latch member  11406  may provide several advantages, similar to the accessory biasing mechanism described above. For example, the force from the latch member  11406  may increase the engagement force between the tag retainer  11400  and the tag  300  at the side opposite the latch member  11406 , and it may increase the frictional force between the tag  300  and the tag retainer  11400 , thereby preventing or limiting rotation, rattling, or other motion of the tag  300  relative to the tag retainer  11400 . 
     The latch member  11406  and the tag  300  may have complementary shapes that allow the latch member  11406  to slide over the battery door of the tag  300  so that the tag  300  and the tag retainer  11400  can be attached and detached by a user. For example, if the tag retainer  11400  is pulled upwards (relative to the orientation shown in  FIG.  114 B ), an interaction between the latch member  11406  and the tag  300  may force the latch member  11406  into its opening in the tag retainer  11400  to allow the tag retainer  11400  to be detached. The opposite operation may occur when the tag retainer  11400  is being attached to the tag  300 . 
       FIG.  115 A  illustrates an example tag  11500  that uses a threaded feature to attach to a tag retainer. The tag  11500  includes a main body portion  11502  (similar to the main body portion  302  of the tag  300 ), and a battery door that includes a threaded feature  11504 . The threaded feature  11504  may be formed of metal, a polymer, or any other suitable material. In some cases, the threaded feature  11504  and the battery door are formed from the same unitary piece of material. 
       FIG.  115 B  illustrates an example tag retainer  11510  configured to attach to the tag  11500  by engaging the threaded feature  11504  of the tag  11500 . The tag retainer  11510  may define an opening  11512  with threads that are configured to engage the threaded feature  11504  of the tag  11500 .  FIG.  115 C  is a partial cross-sectional view of the tag  11500  attached to the tag retainer  11510 . In particular, the tag  11500  may be attached to or detached from the tag retainer  11510  by screwing or unscrewing the tag  11500  from the tag retainer  11510 . 
     As shown in  FIG.  115 C , the tag retainer  11510  may include an insert  11514  that defines the threads. The insert  11514  may be formed of metal, a polymer, or any other suitable material or combination of materials. In some cases, the insert  11514  is stiffer than a material that surrounds the insert  11514  and/or defines the body of the tag retainer  11510 . In other cases, the entire tag retainer  11510  is formed of a single piece of material and the threads are formed directly into the single piece of material. 
       FIG.  115 D  illustrates an example tag  11520  and tag retainer  11522  that uses a similar threaded coupling configuration as the tag  11500  and tag retainer  11510 . Whereas the tag retainer  11510  provided an enclosed recess that covered the tag  11500  (e.g., the battery door of the tag  11500 ), the tag retainer  11510  defines a through-hole that exposes the battery door of the tag  11520  when the tag  11520  is threaded into the threaded opening  11524  of the tag retainer  11522 . In other respects, the tag  11520  and tag retainer  11522  may similar to the tag  11500  and tag retainer  11510 , and for brevity those details may not be repeated here. 
       FIG.  116 A  illustrates an example tag  11600  that uses spring-loaded retention features to attach to an accessory such as a tag retainer. The tag  11600  includes a main body portion  11602  (similar to the main body portion  302  of the tag  300 ), and a battery door  11604 . The battery door  11604 , or any other suitable portion of the tag  11600 , includes spring-loaded retention features  11606 . As shown, the spring-loaded retention features  11606  are arranged about the periphery of a shaft-like portion of the battery door  11604 . 
       FIG.  116 B  is a partial cross-sectional view of the tag  11600  of  FIG.  116 A  when attached to an accessory  11610 , such as a tag retainer. The accessory  11610  may define one or more recesses  11612  that are configured to receive the spring-loaded retention features  11606 . The recesses  11612  may be defined by a single continuous channel extending around the circumference of the opening of the accessory  11610 . In other examples, there may be discrete recesses  11612 , each configured to receive one of the spring-loaded retention features  11606 . The recesses  11612  may be defined by an insert or other member that is attached to or otherwise integrated with another portion of the accessory (as shown). In other example implementations, the accessory is formed of a single piece of material and the recesses are defined in the single piece of material. 
     The tag  11600  may be attached to the accessory  11610  by aligning the tag  11600  with the opening in the accessory  11610  and pressing the tag  11600  and accessory  11610  together until the spring-loaded retention features  11606  slide or roll over the edge of the opening and into the recesses  11612  in the accessory  11610 . The tag  11600  may be detached by reversing these operations, whereupon the spring-loaded retention features  11606  slide or roll out of the recesses  11612  to detach the tag  11600 . 
       FIGS.  116 A- 116 B  show an example in which spring-loaded retention features are positioned on the tag and the recesses are positioned on the accessory. In other implementations, however, these positions may be reversed. For example, the spring-loaded retention features may be integrated with the accessory and the tag may define the recesses that engage the spring-loaded retention features to retain the tag and accessory together. In yet other examples, the tag and the accessory each include both recesses and spring-loaded retention features. 
       FIG.  117 A  illustrates an example tag  11700  having a different form factor than other tags described herein. In particular, the tag  11700  defines a body  11702  (which may include and/or be defined by any number of different housing components). The body  11702  defines two parallel channels  11704  on opposite sides of the body  11702 . As shown, the channels  11704  extend along a diametrical dimension of the tag  11700 , though other positions and/or orientations of the channels  11704  are also possible. In some cases, the channels  11704  are straight (as shown), while in other cases they may be curved or have any other suitable shape. The tag  11700  may be configured to attach to a tag retainer  11710  via the channels  11704 , as shown in  FIG.  117 B . 
       FIG.  117 C  is a partial cross-sectional view of the tag  11700  and tag retainer  11710  of  FIG.  117 B , viewed along line  117 C- 117 C in  FIG.  117 B . The tag retainer  11710  includes two arms  11712  that extend around at least part of the tag  11700  so that engagement ends  11714  of the arms  11712  extend into and engage the channels  11704 . The arms  11712  may be biased towards one another (e.g., with a spring member inside the tag retainer  11710 ) to force the engagement ends  11714  into the channels  11704  and help retain the tag  11700  to the tag retainer  11710 . 
       FIGS.  118 A- 118 C  illustrate an example tag retainer  11800 . The tag retainer  11800  may include a body  11802 , which may be formed from or include a polymer material or other compliant material (including combinations of materials), a cord retainer  11806 , and a cord  11808 . The body  11802  may define an opening  11804  for receiving at least a portion of a tag (e.g., the tag  300 ). The cord  11808  is configured to wrap around a portion of a tag to retain the tag to the tag retainer  11800 . 
       FIG.  118 B  illustrates the tag retainer  11800  attached to the tag  300 . In particular, the tag  300  is positioned in the opening  11804 , and the cord  11808  is wrapped around the tag  300  (e.g., in a housing gap of the tag  300 ). The cord  11808  may also be wrapped around and secured to the cord retainer  11806 .  FIG.  118 C  is a partial cross-sectional view of the tag retainer  11800  of  FIG.  118 B  with the tag  300  attached thereto, viewed along line  118 C- 118 C in  FIG.  118 B .  FIG.  118 C  illustrates how the cord  11808  wraps around the tag  300  (in the housing gap) and the cord retainer  11806  to retain the tag  300  to the tag retainer  11800 . In particular, the size and/or location of the cord  11808  around the tag  300  and relative to the opening  11804  prevents the tag  300  from detaching by passing back through the opening  11804  (e.g., in a downward direction as oriented in  FIG.  118 C ). 
     The cord retainer  11806  may have a clip, fastener, or other mechanism to which the free end of the cord  11808  may be secured after the cord  11808  is wrapped around the tag  300 . The cord  11808  may be secured to the cord retainer  11806  in other ways instead of or in addition to the clip, fastener, or other mechanism. For example, the cord retainer  11806  may have a flange that defines an undercut region, and the cord  11808  may have a size and length such that the cord  11808  is compressed in the undercut region when the cord  11808  is wrapped around the tag  300  (e.g., similar to an envelope closure mechanism). As another example, the cord  11808  may be securely tied and/or knotted to the cord retainer  11806 . 
       FIGS.  119 A- 119 B  illustrate another example tag retainer  11900 . The tag retainer  11900  includes a cord  11902  that is configured to wrap at least partially around a tag in a housing gap, and a retaining ring  11904  that is configured to capture and retain the cord  11902  in the housing gap. The retaining ring  11904  may define an opening  11906  through which the cord  11902  may pass to assist in retaining the cord  11902  to the retaining ring  11904 . The free ends of the cord  11902  may be used to attach the tag to other objects, such as by tying the free ends to the object. 
       FIG.  119 B  is a partial cross-sectional view of the tag retainer  11900  of  FIG.  119 A , shown attached to the tag  300 . The cord  11902  may be wrapped at least partially around the tag  300  in the housing gap of the tag  300 . The retaining ring  11904  may be installed in the housing gap such that it forces the cord  11902  against the tag  300  and retains the cord  11902  in the housing gap. The retaining ring  11904  and the cord  11902  may be sized such that when they are both in the housing gap, they are pressed together and against the tag  300 . The resulting friction between the tag  300 , the cord  11902 , and the retaining ring  11904  hold the cord  11902  and retaining ring  11904  in place. 
     While the position of the retaining ring  11904  in the housing gap helps prevent the cord  11902  from slipping over the top of the battery door of the tag  300 , the opening  11906  in the retaining ring  11904  helps prevent the cord  11902  from unwinding from around the tag  300 . Without passing the cord  11902  through the opening  11906 , for example, a pulling or tugging motion on the cord  11902  could pull the cord  11902  out of the housing gap despite the presence of the retaining ring  11904  in the housing gap. With the cord  11902  situated in the opening  11906 , pulling or tugging forces on the free ends of the cord  11902  will not tend to pull the cord out of the housing gap. Structures or techniques other than the opening  11906  may also be used to prevent pulling forces from detaching the cord. 
       FIGS.  120 A- 120 B  illustrate another example tag retainer  12000 . The tag retainer  12000  may include a body  12002 , which may be formed from or include a polymer material or other compliant material (including combinations of materials). The body  12002  may define an opening  12003  for receiving the tag  300 , and a cord  12006  that passes through cord openings  12004  in the body  12002 . In order to attach the tag  300  to the tag retainer  12000 , the cord  12006  may be untied so that the opening  12003  can be expanded and the tag  300  can be inserted into the opening  12003 . To secure the tag  300 , the cord  12006  may be tied together or otherwise secured, as shown in  FIG.  120 B , to reduce the size of the opening  12003  and hold the body  12002  in the housing gap of the tag  300 . The tag  300  may be removed by untying or otherwise freeing the cord  12006  to allow the opening  12003  to expand for easy removal of the tag  300 . 
       FIGS.  121 A- 121 B  illustrate another example tag retainer  12100 , which is similar to the tag retainer  12000  except that it uses a latching mechanism to retain the free ends of the body together. In particular the tag retainer  12100  includes a body  12102 , which may be formed from or include a polymer material or other compliant material (including combinations of materials). The body  12102 , and in particular arms  12104  of the body  12102 , define an opening  12103  for receiving the tag  300 . The free ends of the arms  12104  define complementary latching features  12106 . As shown in  FIG.  121 B , which is an end view of the tag retainer  12100 , viewed along line  121 B- 121 B in  FIG.  121 A , the latching features  12106  may be engaged with one another to prevent the arms  12104  from separating, thereby holding the arms  12104  together and in place in a housing gap of a tag. One or both of the arms  12104  may be biased in a position that forces the latching features  12106  into secure engagement. For example, the right-hand arm  12104 - 1  (FIG.  121 B) may be biased upwards and to the right, as indicated by arrows  12108 ,  12110 , respectively, relative to the left-hand arm  12104 - 2 . This biasing configuration forces the latching mechanisms into secure engagement, thereby maintaining the arms  12104  in a closed and latched configuration to help retain the tag to the tag retainer  12100 . 
     Many of the example tag retainers described herein are shown as having bodies with substantially uniform thicknesses (e.g., flat, plate- or sheet-like configurations). This is merely one possible configuration for the bodies, and in some cases the bodies may have different shapes and configurations, including shapes that have different thicknesses at different parts of the bodies.  FIG.  122    is a partial cross-sectional view of an example tag retainer  12200  attached to the tag  300 , illustrating an example of a tag retainer with a body having a varying thickness. In particular, the tag retainer  12200  defines an area  12202  of increased thickness proximate the opening that receives the tag  300  (with the greater thickness relative to another area of the tag retainer, such as a handle, strap, or the like). The area of increased thickness is configured to reduce the size of and/or access to the joint between the tag retainer  12200  and the tag  300 , thereby reducing the likelihood of the tag  300  becoming detached due to snagging or other accidental contact. In some cases, the size and/or shape of the increased thickness region is configured so that the transition between the exterior surface of the tag retainer  12200  and the exterior surface of the tag  300  is a continuous curve or line (without substantial gaps, discontinuities, seams, or other areas that may snag on clothes or other objects). As shown in  FIG.  122   , for example, the increased thickness region defines smooth, continuous curved transitions at the top and bottom interfaces  12204 ,  12206  between the tag  300  and the tag retainer  12200 . 
     While  FIG.  122    shows one example tag retainer with an area of increased thickness (to reduce the possibility of accidental detachment of the tag retainer), the same and/or similar configuration may be applied to any other tag retainer described herein. In some cases, the area of increased thickness also results in the tag retainer being stiffer around the opening that receives the tag, which may further increase the strength and/or security of the attachment between the tag and the tag retainer. 
     The tag retainers shown in the figures are often depicted with a strap or elongated attachment portion (e.g., the attachment portion  7004 ,  FIG.  70 A , the strap  7411 ,  FIG.  74 A ). This is merely one example configuration for the tag retainers, however. In some cases, a tag retainer may not include a strap or strap-like feature, and in some cases includes another type of structure to facilitate attachment of the tag retainer to another object. For example, instead of a strap, a tag retainer may have a flat, circular flange to allow the tag retainer to be adhered, sewn, fused (e.g., via laser or ultrasonic welding), or otherwise attached to another object. Further, straps may have configurations other than those shown. For example, straps may have circular or other generally non-flat configurations, and may resemble strings, cords, cables, or the like. Thus, for each of the tag retainers shown herein, it will be understood that the mechanism for attaching the tag retainer to the tag (e.g., the particular configurations of springs, body materials, stiffeners, clips, cords, and the like) may be incorporated in any type of object to facilitate tag attachment. For example, the portion of the body  10202  ( FIGS.  102 A- 102 C ) that defines the opening  10204  (and receives a tag) may be incorporated directly into the material of a purse, backpack, suitcase, briefcase, or the like. In such cases, a distinct strap or other attachment feature need not be provided. 
     As noted above, various tag retainers described herein may be used to attach a wirelessly locatable tag to another object, such as bags, purses, keys, and so forth. In some cases, tag retainers may be provided with clips that facilitate simple and convenient attachment to such objects.  FIGS.  123 A- 123 C  illustrate one such example clip  12300 . For example, the clip  12300  may be attached to the attachment portion  6904  of the tag retainer  6900  ( FIGS.  69 A- 69 C ) by looping the attachment portion  6904  through the central opening of the clip  12300 . 
     The clip  12300  may be formed of a unitary piece of material, such as a single piece of metal. The clip  12300  may define an outer portion  12302  and an inner portion  12304 . The outer and inner portions  12302 ,  12304  may be defined by forming a slit  12306  into the material of the clip  12300 . The slit  12306  may be formed in any suitable manner, such as electrical discharge machining (EDM), plasma cutting, laser cutting, conventional machining or milling, or the like. The slit  12306  may define a small gap, such as equal to or less than about 200 microns, 100 microns, 50 microns, or 10 microns. The clip  12300  may be formed of any suitable material, such as metal (e.g., titanium, steel, aluminum, an alloy, etc.), polymer, carbon fiber, or the like. 
     The inner portion  12304  may be configured to bend or flex relative to the outer portion  12302  in response to an opening force being applied to the inner portion  12304 . For example,  FIG.  123 C  illustrates an opening force  12308  being applied to an actuation region  12310  of the inner portion  12304 . The opening force  12308  causes the inner portion  12304  to flex or bend to define a gap between the inner and outer portions  12304 ,  12302  that allows the clip  12300  to be attached to other objects (e.g., loops on bags, holes in keys, etc.). The inner portion  12304  may be biased towards a closed position (shown in  FIGS.  123 A and  123 B ), such that when the opening force  12308  is removed, the inner portion  12304  returns to the closed position, thereby retaining the clip  12300  to other objects (and/or retaining the objects to the clip  12300 ). 
       FIGS.  124 A- 124 B  illustrate another example clip  12400 . The clip  12400  is similar to the clip  12300  in material, function, and manufacturing, but includes an opening  12408  for attaching to a tag retainer. For example, the attachment portion  6904  of the tag retainer  6900  ( FIGS.  69 A- 69 C ) may be looped through the opening  12408  to attach the clip  12400  to the tag retainer  6900 . 
     The clip  12400  may define an outer portion  12402  and an inner portion  12404 . The outer and inner portions  12402 ,  12404  may be defined by forming a slit  12406  into the material of the clip  12400 . The slit  12406  may be formed in any suitable manner, such as electrical discharge machining (EDM), plasma cutting, laser cutting, conventional machining or milling, or the like. The slit  12406  may define a small gap, such as equal to or less than about 200 microns, 100 microns, 50 microns, or 10 microns. 
     The inner portion  12404  may be configured to bend or flex relative to the outer portion  12402  in response to an opening force being applied to the inner portion  12404 . For example,  FIG.  124 B  illustrates an opening force  12410  being applied to the inner portion  12404 , causing the inner portion  12404  to flex or bend to define a gap between the inner and outer portions  12404 ,  12402  that allows the clip  12400  to be attached to other objects (e.g., loops on bags, holes in keys, etc.). The inner portion  12404  may be biased towards a closed position (shown in  FIG.  124 A ), such that when the opening force  12410  is removed, the inner portion  12404  returns to the closed position, thereby retaining the clip  12400  to other objects (and/or retaining the objects to the clip  12400 ). 
       FIGS.  125 A- 125 B  illustrate another example clip  12500 . The clip  12500  is similar to the clip  12400  in material, function, and manufacturing, and includes an opening  12510  for attaching to a tag retainer. For example, the attachment portion  6904  of the tag retainer  6900  ( FIGS.  69 A- 69 C ) may be looped through the opening  12510  to attach the clip  12500  to the tag retainer  6900 . 
     The clip  12500  may define an outer portion  12502  and an inner portion  12504 . The outer and inner portions  12502 ,  12504  may be defined by forming a slit  12506  into the material of the clip  12500 . The slit  12506  may be formed in any suitable manner, such as electrical discharge machining (EDM), plasma cutting, laser cutting, conventional machining or milling, or the like. The slit  12506  may define a small gap, such as equal to or less than about 200 microns, 100 microns, 50 microns, or 10 microns. 
     The inner portion  12504  may be configured to bend or flex relative to the outer portion  12502  in response to an opening force being applied to the inner portion  12504 . The inner portion  12504  may be biased towards a closed position (shown in  FIG.  125 A ), such that when an opening force is removed, the inner portion  12504  returns to the closed position, thereby retaining the clip  12500  to other objects (and/or retaining the objects to the clip  12500 ). 
     The clip  12500  may also define a lateral guide feature that inhibits the inner portion  12504  from deflecting laterally with respect to adjacent portions of the clip  12500 . For example,  FIG.  125 B  is a detail view of the clip  12500 , showing the area  125 B- 125 B in  FIG.  125 A . The clip  12500  may include a lateral guide  12512  that allows the inner portion  12504  to move inward, along the direction indicated by arrows  12514 , while inhibiting out-of-plane motion along the direction indicated by arrows  12516 . As shown, the lateral guide  12512  is defined by a rail protruding from an end of the inner portion  12504  and a corresponding groove formed in the surface of the clip  12500  opposite the rail. In other examples, the inner portion  12504  may include the groove and the rail may protrude from the location where the groove is shown in  FIG.  125 B . 
       FIGS.  126 A- 126 C  illustrate perspective, front, and side views, respectively, of an example clip  12600  for attaching to a tag retainer. The clip  12600  may be formed of a unitary piece of material, such as a single piece of metal. The clip  12600  may define an opening  12606  for attaching to a tag retainer. For example, the attachment portion  6904  of the tag retainer  6900  ( FIGS.  69 A- 69 C ) may be looped through the opening  12606  to attach the clip  12600  to the tag retainer  6900 . 
     The clip  12600  may define a first ring member  12602  and a second ring member  12604 , which may be biased against each other. The first and second ring members  12602 ,  12604  may operate in a manner similar to a split ring or key ring. For example, objects such as keys, straps, fobs, or the like may be attached to the clip  12600  by spreading the first and second ring members  12602 ,  12604  apart (e.g., at one of the ends  12608 ,  12610 ) and threading the object along one of the ring members until it becomes linked to the clip  12600 . The clip  12600  may be formed of any suitable material, such as metal (e.g., titanium, steel, aluminum, an alloy, etc.), polymer, carbon fiber, or the like. 
       FIGS.  127 A- 127 C  illustrate perspective, front, and side views, respectively, of an example clip  12700  for attaching to a tag retainer. The clip  12700  may be similar in materials and function to the clip  12600 , but instead of being a unitary piece of material, the clip  12700  may be formed by joining two members together. For example, a first member  12702  may be joined to a second member  12704  along a base region  12712 . The first member  12702  may define a first opening  12708  and the second member  12704  may define a second opening  12710  to allow the clip  12700  to operate in a manner similar to a split ring or key ring, as described above with respect to the clip  12600 . The clip  12700  may be formed of any suitable material, such as metal (e.g., titanium, steel, aluminum, an alloy, etc.), polymer, carbon fiber, or the like. The first and second members  12702 ,  12704  may be attached to one another in any suitable manner, such as via welding, soldering, brazing, adhering (e.g., with an epoxy or other adhesive), or the like. 
     The clip  12700  may define an opening  12706  for attaching to a tag retainer. For example, the attachment portion  6904  of the tag retainer  6900  ( FIGS.  69 A- 69 C ) may be looped through the opening  12706  to attach the clip  12700  to the tag retainer  6900 . 
       FIG.  128    illustrates a perspective view of an example ring  12800  for attaching to a tag retainer. The ring  12800  may be a unitary structure that defines a first opening  12804  and a second opening  12806 . The second opening  12806  may be configured for attaching to a tag retainer. For example, the attachment portion  6904  of the tag retainer  6900  ( FIGS.  69 A- 69 C ) may be looped through the second opening  12806  to attach the ring  12800  to the tag retainer  6900 . The first opening  12804  may be used to attach the ring  12800  to another object. For example, a strap, clip, carabiner, zip tie, rope, Velcro strap, or any other suitable member or object may be inserted through the first opening  12804  to attach the ring  12800  to another object. The ring  12800  may be formed of any suitable material, such as metal (e.g., titanium, steel, aluminum, an alloy, etc.), polymer, carbon fiber, or the like. 
     As described herein, the wirelessly locatable tag may be attached to and/or held in one of a variety of accessories or tag retainers. For example, as described above with respect to  FIGS.  69 A- 128   , a lanyard, key fob, luggage tag, belt, band, or other accessory may be adapted to hold or secure the wirelessly locatable tag and facilitate attachment to another object or article. Also, as previously described with respect to some embodiments, an accessory like a lanyard may include one or more snaps or other fasteners that may be engaged to secure, retain, or couple to the wirelessly locatable tag. One or more fasteners like a snap or button may also be used to secure the lanyard or accessory to another object like a piece of luggage, article of clothing, or other personal item. For purposes of the following description, the term “snap” may be used to refer a snap assembly or snap module, which may be formed from two or more subassemblies or modules. For purposes of the following description, the term “wireless tag” may be used to refer to a wirelessly locatable tag or tag, which has been described in detail with respect to various other embodiments, herein. 
       FIGS.  129 A- 129 C  depict an example accessory that may include a snap or other type of fastener. In particular,  FIGS.  129 A- 129 C  depict a lanyard  12900  (also referred to as a tag retainer or holder) that is configured to hold a wireless tag  12950 . The wireless tag  12950  may be similar to the other wirelessly locatable tags or tags described with respect to other embodiments and examples provided herein. As previously described, it may be beneficial to attach the wireless tag  12950  to an article like a piece of luggage, a backpack, a satchel, or other personal item. The lanyard  12900  includes an attachment feature or attachment portion, specifically an attachment ring  12904 , that may be made from a metal material and may be configured to be attached to a strap or other element of the personal item. The lanyard  12900  also includes a pocket  12906  (also referred to as a recess, retaining portion, or tag receptacle portion) or other tag-retaining feature that is configured to hold the wireless tag  12950  securely in the lanyard  12900 , which may allow for wireless tracking of the personal item attached to the lanyard  12900  and wireless tag  12950 . 
     As shown in  FIG.  129 C , the wireless tag  12950  may also be removed from the lanyard  12900  by releasing the snap  12902 , which allows the pocket  12906  to be opened. As described in more detail below, the snap  12902 , also referred to as a snap assembly, may be formed from two assemblies or modules (e.g., male and female assemblies) that are configured to engage each other when pressed together by the user&#39;s fingers. When the snap  12902  is closed or engaged, the snap  12902  secures elements of the lanyard  12900  together, thereby closing the pocket  12906 . As described herein, the elements that are secured together or attached by the snap  12902  may be referred to generically as a first element  12910  and a second element  12912 . In the present example, the first element  12910  and the second element  12912  correspond to different straps or regions of the lanyard  12900  that are secured together by the snap  12902 . As shown in  FIG.  129 C , the snap  12902  may be separated by hand, which allows for the separation of the first element  12910  from the second element  12912  and allows for the pocket  12906  to be opened and allows the wireless tag  12950  to be removed. 
       FIGS.  130 A- 130 H,  131 A- 131 H,  132 A- 132 C, and  133 A- 133 B  depict example fasteners that may be used for an accessory of the wireless tag (e.g., a lanyard), as described herein. In particular, the following embodiments are directed to a mechanical snap fastener that is adapted to attach two elements together using a mechanical engagement between two snap assemblies or modules. As described herein, a snap fastener may be generally referred to as a “snap” and may include two mating snap assemblies or modules, which may be referred to separately as a male module/assembly and a female module/assembly. The female and male modules/assemblies of the snap are configured to couple to one another in order to form a mechanical interlock that is secure enough to remain engaged during ordinary use. The female and male assemblies/modules of the snap may also be disengaged by hand or without the use of special tools. 
     In the embodiment depicted in  FIGS.  130 A- 130 C , the snap  13000 , also referred to as a snap assembly, is used to couple together two accessory elements generally referred to as a first element  13010  and a second element  13012 . In some cases, the first element  13010  is a first portion of a strap and the second element  13012  is a second portion of the same strap or another strap of the accessory. In some cases, the first element  13010  and second element  13012  are separate pieces of different components that are coupled together by the snap  13000 . In other cases, the first element  13010  and the second element  13012  are different portions of a common component that are coupled together by the snap  13000 . Example first and second elements are also described above with respect to the lanyard  12900  of  FIGS.  129 A- 129 C  having a first element  12910  and a second element  12912 . 
     The first element  13010  and the second element  13012  may form part of an accessory that may be generally referred to as a “soft good.” The soft good may be formed at least in part from a pliable or soft material that forms part of the lanyard, key fob, luggage tag, belt, band, or other accessory. The soft good may be formed from a textile, including a woven fabric or other type of cloth made from a network or matrix of fibers, whether natural or synthetic. The soft good may also be formed from a natural or synthetic sheet of a pliable material including, for example, natural rubber, urethane, polypropylene, polyethylene, nylon, silicone, fluoroelastomer, or a variety of other polymers. In some cases, the soft good may be formed from a composite material that includes multiple different materials and may also include non-pliable or rigid materials. The soft good may, for example, include one or more metal components that define clasps, rings, buckles, or other mechanical elements. In some implementations, the first element  13010  and the second element  13012  of the soft good are made from a laminate material having multiple layers that are bonded together. The outer layers may be formed from a softer material to provide comfort or a particular tactile feel and inner layers may have a higher tensile or compressive strength to improve the durability of the soft good. The inner layers may be formed from a high-strength material having a lower modulus of elasticity than the outer layers and may facilitate capture and retention of the snap  13000 . 
     The snap  13000  of  FIGS.  130 A- 130 C  is configured to provide a reliable and consistent mechanical engagement between two elements of the accessory using a mechanism that is both low profile or thin and also configured to be substantially rattle free. The design described with respect to the following embodiments may be contrasted with some traditional snap configurations, which may require significantly more space and may also include elements that may rattle or produce other potentially undesirable sounds. Traditional snaps may also not provide the desired mechanical interconnect and/or the desired tactile feel of the snap configurations that are described herein. 
     As described in more detail below, the snap  13000  may include a compression ring  13002  that provides a retention force to maintain engagement of the snap  13000  when closed. The design and/or integration of the compression ring  13002  may be configured to reduce potentially undesirable noise like rattles and mechanical chatter. In the present embodiment, the compression ring  13002  is at least partially constrained by one or more compliant members  13004 . The compliant member  13004  may help locate the compression ring  13002  while also helping to prevent rattling or other potentially undesirable acoustic effects. The compliant member  13004  may also be used to reduce or prevent the ingress or collection of debris or other foreign matter from accumulating in the snap  13000 . Additionally or alternatively, the compression ring  13002  may also be twisted or have a non-planar shape that helps to reduce potentially undesirable noise. An example of a twisted or non-planar shape is described below with respect to  FIGS.  130 F- 130 H . 
     The compression ring  13002  may be a metal ring having a generally circular shape and a round wire profile. The compression ring  13002 , in this example, is an open-section wire loop formed from a wire member that is bent into a circular shape and having a gap between opposing ends. In some cases, the compression ring  13002  is formed from a spring steel or high-carbon steel and is formed into circular shape having an open end or section that allows for expansion and/or compression of the compression ring  13002 . For purposes of the following embodiments, the term “compression rings” may be used to refer to the compression ring  13002  as it is configured to exert an outward compressive force or retention force on mating components or surfaces. However, the term “compression ring” may also be used to refer to a ring that is configured to exert an inward compressive force, retention force, or other type of force to help maintain engagement of two assemblies of the snap. Elements referred to generally as compression rings may also be referred to as expansion rings, retaining rings, or simply as rings. 
       FIGS.  130 A- 130 C  depict one example embodiment of a snap  13000  that is configured as a low-profile fastener that is substantially rattle free. As shown in  FIGS.  130 A- 130 B , the snap  13000  includes a male assembly  13020  having a compression ring  13002  and a compliant member  13004 . As shown in  FIGS.  130 A- 130 B , the compression ring  13002  is trapped or held within groove  13022  that is formed into the male portion or protrusion component  13024 . The groove  13022  may also be referred to as a recess, pocket, or retaining feature and generally includes at least one wall or surface that is configured to physically constrain the compression ring  13002 . In this case, the groove  13022  is defined by three walls that generally trap or constrain the compression ring  13002 . The three walls include an inner wall that extends between two opposing sidewalls. While the groove  13022  is depicted as having a substantially rectangular profile, the groove  13022  may also have a curved or rounded profile, V profile, or other type of profile shape. The groove  13022  may extend around the circumference of the male portion or protrusion component  13024 , and may be referred to as a circumferential groove. 
     The compression ring  13002  is configured to engage with a mating feature on the female assembly or module  13030 . In the example of  FIGS.  130 A- 130 C , the compression ring  13002  is configured to engage with a tapered or ramped surface  13032  defined along an inner bore of the female assembly  13030 . In general, the ramped surface  13032  is angled in a manner to draw the compression ring  13002  (and the male assembly  13020 ) inward or toward the female assembly  13030  to help maintain the engagement between the male assembly  13020  and the female assembly  13030 . In this example, the tapered or ramped surface  13032  has a draft angle that generally extends outward in a direction that is opposite to the mating male assembly  13020 . While the direction of the draft angle may change depending on the implementation, the tapered or ramped surface  13032  is generally configured to exert a force on the mating assembly that draws the two assemblies of the snap  13000  together. As drawn in  FIGS.  130 A and  130 C , the ramped surface  13032  is configured to draw the compression ring  13002  (and the male assembly  13020 ) downward, which pulls the first element  13010  toward the second element  13012  and maintains engagement between the two elements. The angle of the ramped surface  13032  may be specially configured, along with the spring force of the compression ring  13002 , to provide the desired mechanical engagement between the two assemblies of the snap while also allowing the male and female assemblies  13020 ,  13030  to be disengaged by hand, as necessary. The angle of the tapered or ramped surface  13032  may range from 0.5 degrees to 2 degrees. In some cases, the angle of the ramped surface  13032  ranges from 0.5 to 5 degrees. In some cases, the angle of the ramped surface  13032  ranges from 1 to 5 degrees. In some implementations, a detent feature like a local depression or groove is used instead of or in addition to the ramped surface  13032  in order to help retain the engagement with the compression ring  13002 . 
     As shown in  FIGS.  130 A- 130 B , a compliant member  13004  is positioned at least partially within the groove  13022  with the compression ring  13002 . In this particular implementation, the compliant member  13004  is positioned along the inner wall between the compression ring  13002  and the inner wall of the groove  13022 . In this position, the compliant member  13004  is able to bias the compression ring  13002  in an outward direction with respect to the groove  13022 . This may help maintain consistent or uniform engagement between the compression ring  13002  and the mating surface or surfaces of the female assembly  13030  which, in this case, is the ramped surface  13032 . 
     As shown in  FIGS.  130 A- 130 B , the compliant member  13004  may also locally deflect along an interface that contacts the compression ring  13002  to form a localized depression or groove in the compliant member  13004 . The localized deflection of the compliant member  13004  helps to seat the compression ring  13002  and may help maintain the position of the compression ring  13002  within the groove  13022 , which may help provide reliable or consistent insertion of the male assembly  13020  with the female assembly  13030 . In particular, the compliant member  13004  may help center the compression ring  13002  with respect to the other components of the snap  13000 , which may assist with reliable and consistent operation of the snap  13000 . For example, the compression ring  13002  may help to maintain alignment of a central axis of the compression ring  13002  with respect to a central axis of the mating female assembly  13030 . In the example snap  13000  of  FIGS.  130 A- 130 C , the compression ring  13002  provides the mechanical lead-in or guide as the male assembly  13020  is initially inserted into the female assembly  13030 . In general, the larger the diameter of the compression ring  13002 , the greater the lead-in and the easier it is to align the male and female assemblies  13020 ,  13030 . However, maintaining the location of the compression ring  13002  using the compliant member  13004  allows for a smaller diameter compression ring  13002  in order to achieve the same lead-in or alignment. Using a smaller diameter compression ring  13002  may result in a lower profile or thinner snap  13000  and a more compact design. In this example, the diameter of the wire of the compression ring  13002  ranges from 0.5 mm to 1.5 mm. In some cases, the diameter of the compression ring  13002  ranges from 0.6 mm to 1.2 mm. In some cases, the diameter of the compression ring  13002  ranges from 0.6 mm to 1.0 mm. In some cases, the diameter of the compression ring  13002  ranges from 0.3 mm to 3 mm. 
     The compliant member  13004  may be formed from a compliant or deformable material that is soft enough to be locally deformed by the compression ring  13002  but also stiff enough to provide structural support and help constrain the compression ring  13002  within the groove  13022 . The compliant member  13004  may be formed from an elastic material. In some implementations, the compliant member  13004  may be formed from a natural rubber or a synthetic or partially synthetic elastomer including, for example, silicone, neoprene Nitrile rubber, Butyl rubber, Poron, ethylene propylene (EPM) rubber, ethylene-vinyl acetate (EVA), fluorosilicone rubber, or other similar materials. In some cases, the compliant member  13004  is formed from multiple materials or has a composite construction that may include one or more polymers and/or one or more other materials. 
       FIGS.  130 D and  130 E  depict alternative arrangements of a compliant member with respect to a compression ring. In  FIG.  130 D , a compliant member  13004   d  is positioned along the rear or inner wall and one side wall of the groove  13022   d . In this example, the compliant member  13004   d  is able to exert a force (e.g., a biasing force) that is outward and upward, as drawn in  FIG.  130 D . Stated another way, the compliant member  13004   d  is configured to provide a biasing force that tends to push the compression ring  13002   d  outward from the groove  13022   d  and also toward an opposing wall or side wall of the groove  13022   d . The compliant member  13004   d  and the resulting exerted force may function in a similar manner as previously described to help constrain the compression ring  13002   d  within the groove  13022   d . Specifically, the compliant member  13004   d  may provide a biasing force that reduces potentially undesirable noise (e.g., a rattle). Additionally, because the biasing force has a component that is transverse to a central axis of the snap  13000 , the biasing force provided by the compliant member  13004   d  may tend to center the compression ring  13002   d  within the snap  13000  (e.g., maintain alignment of the central axis of the compression ring  13002   d  with respect to a central axis of the snap  13000 . 
     In  FIG.  130 E , a compliant member  13004   e  is positioned along one side wall of the groove  13022   e . In this example, the compliant member  13004   e  is able to exert a (biasing) force that is substantially parallel with a central axis of the compression ring  13002   e  (e.g., in an upward direction, as drawn in  FIG.  130 E ). Stated another way, the compliant member  13004   e  is configured to provide a biasing force that tends to push the compression ring  13002   e  toward an opposing wall or side wall of the groove  13022   e . The compliant member  13004   e  and the resulting exerted force may function in a similar manner as previously described to help constrain the compression ring  13002   e  within the groove  13022   e . Similar to the previous example, the compliant member  13004   e  may apply a biasing force on the compression ring  130002   e  to reduce potentially undesirable rattles or noise. However, because the biasing force provided by the compliant member  13004   e  is substantially parallel to a central axis of the snap, the compliant member  13004   e  may not provide a biasing force component that tends to center the compression ring  13002   e  within the snap. The configurations and locations of the compliant members described in each of these embodiments are provided by way of example and are not exhaustive of all the configurations and mounting scenarios that may be used. 
     The snap  13000  includes various components and elements that are used to couple the snap  13000  to the accessory. As shown in  FIGS.  130 A- 130 B , male assembly  13020  includes an outer flange  13025  and an inner flange  13026  that are configured to engage and capture a respective portion of the first element  13010 . The outer flange  13025  and the inner flange  13026  secure the male assembly  13020  within a respective hole formed in the first element  13010 . One or both the outer flange  13025  or the inner flange  13026  may include one or more engagement features that may include one or more ribs, teeth, grooves, or protruding features that are configured to mechanically engage material of the first element  13010 . The engagement features may be configured to extend into the material of the first element  13010  in order to provide a bite or anchor for the male assembly  13020 . As described previously, the first element  13010  may be formed from a laminate material and may include one or more internal layers that have an improved tensile and/or compressive strength or a reduced elastic modulus, which may help maintain engagement with the outer flange  13025  and the inner flange  13026  of the male assembly  13020 . In some cases, the inner materials form a bottom surface of the recess formed in the first element  13020 , which may engage the one or more engagement features of the outer flange  13025  and/or the inner flange  13026 . 
     The design of the flanges ( 13025 ,  13026 ,  13035 ,  13036 ) and/or the material of the first element  13010  and the second element  13012  may result in a snap  13000  that is substantially smaller than some traditional designs. In some examples, the amount of overlap between the flanges ( 13025 ,  13026 ,  13035 ,  13036 ) of the respective portions of the first element  13010  and the second element  13012  may be approximately half of a traditional overlap. In some cases, the overlap is less than 3 mm. In some cases, the overlap is less than 2.5 mm. In some cases, the overlap is less than 2 mm. In some cases, the overlap is approximately 1.5 mm or less. 
     As shown in  FIGS.  130 A- 130 B , the outer flange  13025  may be formed by an outer component  13027  that also defines an outer or exterior surface of the snap  13000 . The inner flange  13026  is formed as part of an inner component  13028  that forms an inner surface of the male assembly  13020 . The outer component  13027  may be directly coupled to the inner component  13028  using an adhesive, weld, press fit, threaded connection, or other structurally coupling technique. In some cases, one or more intermediate elements or components is used to couple the outer component  13027  to the inner component  13028 . In this example, the protrusion component  13024  is attached to the outer component  13027  using a press or interference fit. The protrusion component  13024  may also be attached to the outer component  13027  using an adhesive, weld, threaded connection, or other attachment technique. In this example, the protrusion component  13024  and the outer component  13027  cooperate to define the groove  13022 . In alternative embodiments, the groove  13022  may be formed entirely within either the protrusion component  13024  or the outer component  13027 . 
     Similarly, as shown in  FIGS.  130 A and  130 C , the female assembly  13030  is formed from multiple components. Specifically, the female assembly  13030  includes an outer flange  13035  and an inner flange  13036  that are configured to engage and capture a respective portion of the second element  13012 . Similar to the previous example described above, the outer flange  13035  and/or the inner flange  13036  may have one or more engagement features (e.g., ribs, teeth, grooves, protruding features) that help mechanically engage the respective flange with the second element  13012 . The outer flange  13035  and the inner flange  13036  secure the female assembly  13030  within a respective hole formed in the second element  13012 . As shown in  FIGS.  130 A and  130 C , the outer flange  13035  may be formed by an outer component  13037  that also defines an outer or exterior surface of the snap  13000 . The inner flange  13036  is formed as part of an inner component  13038  that forms an inner surface of the female assembly  13030 . The outer component  13037  may be directly coupled to the inner component  13038  using an adhesive, weld, press fit, threaded connection, or other structurally coupling technique. In some cases, one or more intermediate elements or components is used to couple the outer component  13037  to the inner component  13038 . 
     In this example, the inner component  13038  and the outer component  13037  cooperate to define a bore or opening that receives the protrusion component  13024  of the male assembly  13020 . The inner component  13038  also defines the ramped surface  13032  that is configured to engage the compression ring  13002 . The inner component  13038  also includes a chamfer  13039  or lead-in feature formed along the inner surface as a lead-in to the bore or opening that receives the male assembly  13020 . The chamfer  13039  is configured to engage with the leading edge of the male assembly  13020 , which may also include a similar chamfer or lead-in to facilitate alignment of the two assemblies  13020 ,  13030  when being snapped together or coupled. The chamfer  13039  may also be configured to engage with the compression ring  13002  and compress the compression ring  13002  inward while the two assemblies  13020 ,  13030  are being snapped together or coupled. 
     As shown in  FIGS.  130 A- 130 C , an outer surface of the protrusion component  13024  is exposed along an exterior surface of the snap  13000 . That is, protrusion component  13024  is configured to extend through the bore or opening defined by the female assembly  13030  to define an exterior surface of the snap  13000 . Also as shown in  FIG.  130 A , the exposed or exterior surface of the protrusion component  13024  is substantially aligned with an exposed or exterior surface of the outer component  13037  of the female assembly  13030 . In this example, the exposed or exterior surface of the protrusion component  13024  may also be described as being flush with an exposed or exterior surface of the outer component  13037  of the female assembly  13030 . In some implementations, the protrusion component  13024  and the outer component  13037  of the female assembly  13030  cooperate to define a curved or non-planar profile. 
     The snap  13000  is also configured so that an inner surface of the first element  13010  contacts and seats against an inner surface of the second element  13012  when the male assembly  13020  is engaged with the female assembly  13030 . As shown in  FIG.  130 A , the male assembly  13020  is separated from the female assembly  13030  by a small gap or space. This prevents contact between the two assemblies, which may also reduce rattling or other potentially undesirable effects during use. By seating the inner surfaces of the first and second elements  13010 ,  13012 , the snap  13000  may snap together with a muted or softened feel (rather than a hard or sharp click). The small gap or space between the male assembly  13020  and the female assembly  13030  may also reduce wear between the two components and also help preserve any surface finish or surface treatment on the respective components. 
     The various components of the snap  13000  may be formed from a variety of materials. In some implementations, the inner components  13028 ,  13038  and the outer components  13027 ,  13037  are formed from a metal material. The metal material may be a stainless steel, carbon steel, aluminum, titanium, or other metal or metal alloy. In some implementations, the outer components  13027 ,  13037  or exposed surfaces of the outer components  13027 ,  13037  are polished to provide a smooth finish along the exterior of the snap  13100 . In some cases, one or more of the components are formed from a polymer or other synthetic material. For example, one or more of the components may be partially or fully over molded with a plastic material to improve the appearance and or tactile feel of the snap  13000 . In some cases, one or more of the components are formed entirely from a plastic material. 
       FIGS.  130 F- 130 H  depict another example snap  13050 , also referred to as a snap assembly, that may be substantially rattle free. Many of the components and elements of the example snap  13050  are similar to the example snap  13000  described above, and a description of such similar elements are omitted to reduce redundancy and improve clarity. Similar to the previous example, the snap  13050  includes a male assembly  13070  that is inserted into and engaged with a female assembly  13080 . Also similar to the previous example, the male assembly  13070  includes a groove  13082  that retains or captures a compression ring  13052 . 
     In the examples of  FIGS.  130 F- 130 H , the compression ring  13052  is twisted or bent to define a non-flat or non-planar shape. Specifically, as shown in  FIGS.  130 G- 130 H  the compression ring  13052  is an open-section ring or wire loop having opposing ends. The ends may be set apart by a gap and the ends of the ring, in this example, are displaced to define an offset D 1 . The compression ring  13052  may be described as having a partially helical shape, non-planar profile, or otherwise non-flat shape. This out-of-plane distortion or displacement helps constrain the compression ring  13052  within the groove  13082  so that the compression ring  13052  cannot move freely and cause a potentially undesirable rattle or chatter. The offset D 1  may be greater than the clearance between the diameter of the compression ring  13052  and the opposing walls of the groove  13082 . In some cases, the offset D 1  is less than 0.5 mm. In some cases, the offset D 1  is less than 0.4 mm. In some cases, the offset D 1  is less than 0.3 mm. The offset D 1  may also be described with respect to the wire diameter of the open-section wire loop. In some cases, the offset D 1  ranges from 10% to 50% of the wire diameter. In some cases, the offset D 1  ranges from 15% to 40% of the wire diameter. In some cases, the offset D 1  ranges from 20% to 30% of the wire diameter. As shown in  FIG.  130 F , the twist or non-flat shape results in the compression ring  13052  contacting an upper wall of the groove  13082  for one portion of the groove  13082  and also contacting a lower wall of the groove  13082  for another portion of the groove  13082 , which helps to constrain the compression ring  13052  along an axial direction (as defined by a central axis of the snap  13050 ). 
     The compression ring  13052  may have other non-flat or non-planar shapes that similarly constrain the compression ring  13052  within the groove  13082 . For example, the compression ring  13052  may have a wavy shape, U-shape, or other non-flat shape that results in the compression ring  13052  contacting both opposing sidewalls of the groove  13082  in order to constrain the compression ring  13052  along the axial direction and reduce potential rattles or chatter. In some cases, the snaps  13000 ,  13050  include both a compliant member (as described above with respect to  FIGS.  130 A- 130 E ) and a non-flat shape (as described with respect to  FIGS.  130 F- 130 H ). 
       FIGS.  131 A- 131 C  depict another configuration of a snap  13100 , also referred to as a snap assembly, having a low-profile and substantially rattle-free design. Many of the same or similar features described above with respect to snap  13000  also apply to the snap  13100 , and a description of which are not repeated to reduce redundancy. Similar to the other embodiments described herein, the snap  13100  may be integrated with or incorporated into an accessory or soft good including, for example, a lanyard, key fob, luggage tag, belt, band, or other accessory. The snap  13100  may also be formed from similar materials and function in a similar fashion as described above with respect to  FIGS.  130 A- 130 C . 
     Similar to the previous example, the snap  13100  includes a male assembly  13120  and a female assembly  13130 . Also similar to the previous example, the snap  13100  includes a compression ring  13102  and a compliant member  13104  that are positioned at least partially within a groove  13132 . In this example, instead of a groove being formed into a protrusion component of the male assembly, the groove  13132  is formed into a component of the female assembly  13130 . Also, instead of exerting an outward force, the compression ring  13102  of the snap  13100  is configured to exert a (retaining) force in an inward direction toward ramped surface  13122  that is defined along a surface of the protrusion component  13124  of the male assembly  13120 . The groove  13132  may extend around the circumference of the female assembly  13130 , and may be referred to as a circumferential groove. 
     In the example snap  13100  of  FIGS.  131 A- 131 C , the compression ring  13102  is at least partially constrained by the compliant member  13104 . As shown in  FIGS.  131 A and  131 C , the compliant member  13104  may locally deflect along an interface that contacts the compression ring  13102  to form a localized depression or groove in the compliant member  13104 . The localized deflection of the compliant member  13104  helps to seat the compression ring  13102  and may help maintain the position of the compression ring  13102  within the groove  13122 , which may help provide reliable or consistent insertion of the male assembly  13120  with the female assembly  13130 . In particular, the compliant member  13104  may help center the compression ring  13102  with respect to the other components of the snap  13100 , which may assist with reliable and consistent operation of the snap  13100 . Similar to the previous example, the compression ring  13102  provides the mechanical lead-in or guide as the male assembly  13120  is initially inserted into the female assembly  13130 . Maintaining the location of the compression ring  13102  and supporting the compression ring  13102  using the compliant member  13104  may allow for a smaller diameter compression ring  13102  than would ordinarily be used. 
       FIGS.  131 D and  131 E  depict alternative arrangements of a compliant member with respect to a compression ring. In  FIG.  131 D , a compliant member  13104   d  is positioned along the rear or inner wall and one side wall of the groove  13122   d . In this example, the compliant member  13104   d  is able to exert a force (e.g., a biasing force) that is outward and upward, as drawn in  FIG.  131 D . Stated another way, the compliant member  13104   d  is configured to provide a biasing force that tends to push the compression ring  13102   d  outward from the groove  13122   d  and also toward an opposing wall or sidewall of the groove  13122   d . The compliant member  13104   d  and the resulting exerted force may function in a similar manner as previously described to help constrain the compression ring  13102   d  within the groove  13122   d . Specifically, the compliant member  13104   d  may provide a biasing force that reduces potentially undesirable noise (e.g., a rattle). Additionally, because the biasing force has a component that is transverse to a central axis of the snap, the biasing force provided by the compliant member  13104   d  may tend to center the compression ring  13102   d  within the snap. 
     In  FIG.  131 E , a compliant member  13104   e  is positioned along one sidewall of the groove  13122   e . In this example, the compliant member  13104   e  is able to exert a (biasing) force that is upward, as drawn in  FIG.  131 E . Stated another way, the compliant member  13104   e  is configured to provide a biasing force that tends to push the compression ring  13102   e  toward an opposing wall or side wall of the groove  13122   e . The compliant member  13104   e  and the resulting exerted force may function in a similar manner as previously described to help constrain the compression ring  13102   e  within the groove  13122   e . The compliant member  13104   e  and the resulting exerted force may function in a similar manner as previously described to help constrain the compression ring  13102   e  within the groove  13122   e . Similar to the previous example, the compliant member  13104   e  may apply a biasing force on the compression ring  131002   e  to reduce potentially undesirable rattles or noise. However, because the biasing force provided by the compliant member  13104   e  is approximately parallel to a central axis of the snap, the compliant member  13104   e  may not provide a biasing force component that tends to center the compression ring  13102   e  within the snap The configurations and locations of the compliant members described in each of these embodiments are provided by way of example and are not exhaustive of all the configurations and mounting scenarios that may be used. 
     The snap  13100  includes various components and elements that are used to couple the snap  13000  to the accessory. In particular, the snap  13100  also includes mounting flanges that couple the male and female assemblies  13120 ,  13130  to the respective first and second elements  13110 ,  13112 . As shown in  FIGS.  131 A- 131 B , the male assembly  13120  includes an outer flange  13125  and an inner flange  13126  that are configured to engage and capture a respective portion of the first element  13110 . The outer flange  13125  and the inner flange  13126  secure the male assembly  13120  within a respective hole formed in the first element  13110 . Similar to the previous examples described above, the outer flange  13125  and/or the inner flange  13126  may have one or more engagement features (e.g., ribs, teeth, grooves, protruding features) that help mechanically engage the respective flanges with the first element  13110 . 
     As shown in  FIGS.  131 A- 131 B , the outer flange  13125  may be formed by part of the protrusion component  13124  that also defines an outer or exterior surface of the snap  13100 . The inner flange  13126  is formed as part of an inner component  13128  that forms an inner surface of the male assembly  13120 . The protrusion component  13124  may be directly coupled to the inner component  13128  using an adhesive, weld, press fit, threaded connection, or other structurally coupling technique. In some cases, one or more intermediate elements or components is used to couple the protrusion component  13124  to the inner component  13128 . 
     As shown in  FIGS.  131 A and  131 C , the female assembly  13130  is formed from multiple components. Specifically, the female assembly  13130  includes an outer flange  13135  and an inner flange  13136  that are configured to engage and capture a respective portion of the second element  13112 . The outer flange  13135  and the inner flange  13136  secure the female assembly  13130  within a respective hole formed in the second element  13112 . Similar to the previous examples described above, the outer flange  13135  and/or the inner flange  13136  may have one or more engagement features (e.g., ribs, teeth, grooves, protruding features) that help mechanically engage the respective flange with the second element  13112 . 
     As shown in  FIGS.  131 A and  131 C , the outer flange  13135  may be formed by an outer component  13137  that also defines an outer or exterior surface of the snap  13100 . The inner flange  13136  is formed as part of an inner component  13138  that forms an inner surface of the female assembly  13130 . The outer component  13137  may be directly coupled to the inner component  13138  using an adhesive, weld, press fit, threaded connection, or other structurally coupling technique. In some cases, one or more intermediate elements or components is used to couple the outer component  13137  to the inner component  13138 . 
     In this example, the inner component  13138  and the outer component  13137  cooperate to define a bore or opening that receives the protrusion component  13124  of the male assembly  13120 . As shown in  FIGS.  131 A- 131 B , the protrusion component  13124  includes a chamfer  13129  that may facilitate alignment and insertion of the male assembly  13120  into the female assembly  13130 . The chamfer  13139  is configured to engage with the leading edge of the female assembly  13130 , which may also include a similar chamfer or lead-in to facilitate alignment of the two assemblies  13120 ,  13130  when being snapped together or coupled. The chamfer  13139  may also be configured to engage with the compression ring  13102  and compress the compression ring  13102  inward while the two assemblies  13120 ,  13130  are being snapped together or coupled. 
     The protrusion component  13124  also includes a ramped surface  13122 , which is configured to engage with the compression ring  13102  and may help retain engagement between the male assembly  13120  into the female assembly  13130 . In general, the ramped surface  13122  is angled in a manner to draw the compression ring  13102  (and the female assembly  13130 ) inward or toward the male assembly  13130  to help maintain the engagement between the male assembly  13120  and the female assembly  13130 . In this example, the tapered or ramped surface  13122  has a draft angle that generally extends outward in a direction that is opposite to the base of the protrusion component  13124  of the male assembly  13120 . While the direction of the draft angle may change depending on the implementation, the tapered or ramped surface  13122  is generally configured to exert a force on the mating assembly that draws the two assemblies of the snap  13100  together. In some implementations, a detent feature like a local depression or groove is used instead of or in addition to the ramped surface  13122  in order to help retain the engagement with the compression ring  13102   
     As shown in  FIG.  131 A , an outer surface of the protrusion component  13124  is exposed along an exterior surface of the snap  13100 . That is, protrusion component  13124  is configured to extend through the bore or opening defined by the female assembly  13130  to define an exterior surface of the snap  13100 . Also as shown in  FIG.  131 A , the exposed or exterior surface of the protrusion component  13124  is substantially aligned with an exposed or exterior surface of the outer component  13137  of the female assembly  13130 . In this example, the exposed or exterior surface of the protrusion component  13124  may be described as being flush with an exposed or exterior surface of the outer component  13137  of the female assembly  13130  In some implementations, the protrusion component  13124  and the outer component  13137  of the female assembly  13130  cooperate to define a curved or non-planar profile. 
     The snap  13100  is also configured so that an inner surface of the first element  13110  contacts and seats against an inner surface of the second element  13112  when the male assembly  13120  is engaged with the female assembly  13130 . As shown in  FIG.  131 A , the male assembly  13120  is separated from the female assembly  13130  by a small gap or space. This prevents contact between the two assemblies, which may also reduce rattling or other potentially undesirable effects during use. By seating the inner surfaces of the first and second elements  13110 ,  13112 , the snap  13100  may snap together with a muted or softened feel (rather than a hard or sharp click). As described previously, the small gap or space between the male assembly  13120  and the female assembly  13130  may also reduce wear between the two components and also help preserve any surface finish or surface treatment on the respective components. 
       FIGS.  131 F- 131 H  depict another example snap  13150 , also referred to as a snap assembly, that may be substantially rattle free. Many of the components and elements of the example snap  13150  are similar to the example snap  13100  described above, and a description of such similar elements are omitted to reduce redundancy and improve clarity. Similar to the previous example, the snap  13150  includes a male assembly  13170  that is inserted into and engaged with a female assembly  13180 . Also similar to the previous example, the male assembly  13170  includes a groove  13182  that retains or captures a compression ring  13152 . 
     In the examples of  FIGS.  131 F- 131 H , the compression ring  13152  is twisted or bent to define a non-flat or non-planar shape. Specifically, as shown in  FIGS.  131 G- 131 H , the compression ring  13152  is an open-section ring or wire loop having opposing ends. The ends may be set apart by a gap and the ends of the ring, in this example, are displaced to define an offset D 1 . The compression ring  13152  may be described as having a partially helical shape, non-planar profile, or otherwise non-flat shape. This out-of-plane distortion or displacement helps constrain the compression ring  13152  within the groove  13182  so that the compression ring  13152  cannot move freely and cause a potentially undesirable rattle or chatter. The offset D 1  may be greater than the clearance between the diameter of the compression ring  13152  and the opposing walls of the groove  13182 . In some cases, the offset D 1  is less than 0.5 mm. In some cases, the offset D 1  is less than 0.4 mm. The offset D 1  may also be described with respect to the wire diameter of the open-section wire loop. In some cases, the offset D 1  ranges from 10% to 50% of the wire diameter. In some cases, the offset D 1  ranges from 15% to 40% of the wire diameter. In some cases, the offset D 1  ranges from 20% to 30% of the wire diameter. In some cases, the offset D 1  is less than 0.3 mm. As shown in  FIG.  131 F , the twist or non-flat shape results in the compression ring  13152  contacting an upper wall of the groove  13182  for one portion of the groove  13182  and also contacting a lower wall of the groove  13182  for another portion of the groove  13182 , which helps to constrain the compression ring  13152  along an axial direction (as defined by a central axis of the snap  13150 ). 
     The compression ring  13152  may have other non-flat or non-planar shapes that similarly constrain the compression ring  13152  within the groove  13182 . For example, the compression ring  13152  may have a wavy shape, U-shape, or other non-flat shape that results in the compression ring  13152  contacting both opposing sidewalls of the groove  13182  in order to constrain the compression ring  13152  along the axial direction and reduce potential rattles or chatter. In some cases, the snaps  13100  and  13150  include both a compliant member (as described above with respect to  FIGS.  131 A- 131 E ) and a non-flat shape (as described with respect to  FIGS.  131 F- 131 H ). 
     As described above, the snaps  13000 ,  13050 ,  13100 , and  13150  of  FIGS.  130 A- 130 H and  131 A- 131 H , also referred to as snap assemblies, may result in an overall reduced size or footprint of the snap assembly. In these examples, the overall height or thickness of the snaps ( 13000 ,  13050 ,  13100 , and  13150 ) may be less than 6 mm thick. In some implementations, the overall height or thickness of the snaps ( 13000 ,  13050 ,  13100 , and  13150 ) may be less than 5 mm thick. In some implementations, the overall height or thickness of the snaps ( 13000 ,  13050 ,  13100 , and  13150 ) may be less than 4 mm thick. The overall diameter or profile of the snaps ( 13000 ,  13050 ,  13100 , and  13150 ) may also be reduced as compared to some traditional designs. In these examples, the overall diameter of the snaps ( 13000 ,  13050 ,  13100 , and  13150 ) may be less than 15 mm. In some implementations, the overall diameter of the snaps ( 13000 ,  13050 ,  13100 , and  13150 ) may be less than 12 mm. In some implementations, the overall diameter of the snaps ( 13000 ,  13050 ,  13100 , and  13150 ) may be less than 10 mm. Further, as described previously, the overlap between the respective snap flange and the portion of the soft good material may also be reduced as compared to some traditional snap designs. In some examples, the amount of overlap between the flange and the soft good material may be approximately half of a traditional overlap. In some cases, the overlap is less than 3 mm. In some cases, the overlap is less than 2.5 mm. In some cases, the overlap is less than 2 mm. In some cases, the overlap is approximately 1.5 mm or less. 
       FIGS.  132 A- 132 C and  133 A- 133 B  depict additional snap embodiments that may be used for an accessory of a wireless tab. In particular,  FIGS.  132 A- 132 B  depict an example snap  13200 , also referred to as a snap assembly, having a compression ring  13202 . The snap  13200  includes a single-piece or integrally formed male assembly  13220  and a single-piece or integrally formed female assembly  13230 . Either or both of the male assembly  13220  and the female assembly  13230  may be formed from a stamped sheet metal member. The snap  13200  also includes partially molded end caps  13240  and  13250  that define exterior surfaces of the snap  13200  and that are attached to the male assembly  13220  and female assembly  13230  respectively. Similar to examples previously described, the snap  13200  is configured to couple a first element  13210  to a second element  13212 , which may be two elements or regions of an accessory, as described previously. 
     As shown in  FIGS.  132 A- 132 B , the male assembly  13220  includes features that are configured to engage with the female assemble  13230  and the compression ring  13202  in a similar fashion as described above with respect to the other snap embodiments. In particular, the male assembly  13220  includes a ramped surface  13222  or other feature that is configured to engage with the compression ring  13202  when the snap  13200  is closed and the male and female assemblies  13220 ,  13230  are coupled. While a ramped surface  13222  is used in this example, the male assembly  13220  may also include a groove, detent, recess, or other similar feature that is configured to engage with the compression ring  13202  in order to help maintain engagement between the male and female assemblies  13220 ,  13230  of the snap  13200 . 
     The snap includes a male assembly  13220  that is integrally formed as a single unitary element. The unitary element includes a protrusion portion defining the ramped surface  13222  and an inner flange  13224  that is configured to help retain the male assembly  13220  to the first element  13210 . The male assembly  13220  may be stamped from a single monolithic sheet of metal and may be formed from a stainless steel, carbon steel, brass, or other material that can be formed into the geometry of the male assembly  13220  shown in  FIGS.  132 A- 132 B . In some cases the male assembly  13220  is formed from an aluminum material and may also be machined in order to form one or more of the features shown in  FIGS.  132 A- 132 B . 
     The male assembly  13220  is also attached to an end cap  13240 , which defines an exterior cosmetic surface of the snap  13200 . The male assembly  13220  may be attached to a rib  13244  of the end cap using an ultrasonic weld, laser weld, press fit, interference fit, adhesive, or other bonding technique. A cap top  13242  may be formed from a plastic material that is over molded over the rib  13244 . The cap top  13242  may have a surface finish and color suitable for cosmetic and tactile requirements of the snap  13200 . The cap top  13242  may also form an upper flange  13246  that helps retain the male assembly  13220  to the first element  13210 . Similar to previous embodiments described herein, a portion of the first element  13210  is positioned between or sandwiched by the inner flange  13224  and the outer flange  13246  in order to retain the male assembly  13220 . 
     The snap  13200  also includes a female assembly  13230  that is integrally formed as a single unitary element. The unitary element of the female assembly  13230  includes a recess or pocket portion that is configured to receive the protrusion of the male assembly  13220 . The unitary element of the female assembly  13230  also forms an inner flange  13234  that is configured to help retain the female assembly  13230  to the second element  13212 . The female assembly  13230  may be stamped from a single monolithic sheet of metal and may be formed from a stainless steel, carbon steel, brass, or other material that can be formed into the geometry of the female assembly  13230  shown in  FIGS.  132 A- 132 B . In some cases the female assembly  13230  is formed from an aluminum material and may also be machined in order to form one or more of the features shown in  FIGS.  132 A- 132 B . 
     The female assembly  13230  is also attached to an end cap  13250 , which defines an exterior cosmetic surface of the snap  13200 . The female assembly  13230  may be attached to a rib  13254  of the end cap using an ultrasonic weld, laser weld, press fit, interference fit, adhesive, or other bonding technique. A cap top  13252  may be formed from a plastic material that is over molded over the rib  13254 . The cap top  13252  may have a surface finish and color suitable for cosmetic and tactile requirements of the snap  13200 . The cap top  13252  may also form an upper flange  13256  that helps retain the female assembly  13230  to the second element  13212 . Similar to previous embodiments described herein, a portion of the second element  13212  is positioned between or sandwiched by the inner flange  13234  and the outer flange  13256  in order to retain the female assembly  13230 . 
     In this example, the female assembly  13230  includes a recess  13232  that receives the compression ring  13202 . The recess  13232 , also referred to as a groove, may be integrally formed from a bent or stamped region of the female assembly  13230 . The recess  13232  may also be machined or formed using another suitable manufacturing technique. While not depicted in  FIGS.  132 A- 132 B , the snap  13200  may also include a compliant member that is also positioned within the recess  13232  and may help to locate or maintain the position of the compression ring  13202 . As discussed previously, the compliant member may reduce snap rattle and, depending on the configuration, also help to center the compression ring  13202 . While not depicted in  FIGS.  132 A- 132 B  to reduce redundancy, any of the compliant member configurations described above with respect to  FIGS.  130 A- 130 E and  131 A- 131 E  may also be applied to snap  13200  depicted in  FIGS.  132 A- 132 B . Similarly, the compression ring  13202  may have a twisted, partially helical, non-flat, or non-planar shape that helps to reduce rattle, chatter, or other potentially undesirable noises. A description of such a compression ring is described above with respect to  FIGS.  130 F- 130 H and  131 F- 131 H  and a similar compression ring configuration may also be applied to snap  13200  depicted in  FIGS.  132 A- 132 B . 
     As shown in  FIGS.  132 A- 132 B , the first element  13210  and the second element  13212  include a pocket  13214 ,  13216 , respectively. The pockets  13214 ,  13216  may be formed as part of a molding process or, alternatively, may be machined into the first and second elements  13210 ,  13212 , respectively. The pockets  13214 ,  13216  may have a depth that is greater than the respective inner flanges  13224 ,  13234 , which allows for the first element  13210  to seat directly on or contact the second element  13212  when the snap  13200  is engaged or closed. This may prevent contact between the male assembly  13220  and the female assembly  13230 , which may help reduce undesired noises and improve the feel of the snap, when engaging the male and female assemblies  13220 ,  13230 . 
       FIG.  132 C  depicts another example embodiment of a snap  13260 , also referred to as a snap assembly. The snap  13260  of  FIG.  132 C  is similar to the stamped snap example described above with respect to  FIGS.  132 A and  132 B  except that the snap  13260  features a protrusion component or element  13276  that extends through the female assembly  13280  and defines an external surface of the snap  13260 . As shown in  FIG.  132 C , the protrusion component or element  13276  defines an external surface that is substantially flush or aligned with an external surface of the female assembly  13280 . This may provide a desired aesthetic appearance and also improve the engagement between the male assembly  13270  and the female assembly  13280  while also maintaining a thin or low-profile form factor of the snap  13260 . 
     Similar to the previous examples, the snap  13260  includes a male assembly  13270  that is inserted into and engaged with a female assembly  13280 . A compression ring  13262  engages a ramped or tapered surface on the protrusion component or element  13276  in order to help maintain engagement between the male assembly  13270  and the female assembly  13280 . Similar to the previous examples, the compression ring  13262  may be retained within a groove or recess and rattle may be reduced by using a compliant member or compression ring having a twisted or non-flat shape. A similar description of such features have been described above and are not repeated here to reduce redundancy. 
     As shown in  FIG.  132 C , the snap  13260  includes a molded cap  13272  that is insert molded over internal member  13274 . The internal member  13274  may include one or more holes or other features into which the insert molded cap  13272  may flow into and provide a more robust engagement between the two components. The molded cap  13272  may define a portion of a flange that is configured to engage the soft good. Similar to the other examples described herein, the flange may include various engagement features including, for example, ribs, teeth, grooves, or protruding features that help maintain engagement between the snap  13260  and the respective portion of the soft good. The snap  13260  also includes other flanges  13284 ,  13286  that may also include one or more engagement features to help maintain engagement between the snap  13260  and the respective portion of the soft good. 
       FIGS.  133 A- 133 B  depict another embodiment of a snap  13300 , also referred to as a snap assembly, that may be used in an accessory of a wireless tag. In particular,  FIGS.  133 A- 133 B  depict a snap  13300  that includes a magnetic coupling rather than a compression ring engagement between the components of the snap  13300 . Many of the elements and features of the snap  13300  are similar to those described above with respect to the snap  13200  of  FIGS.  132 A- 132 B . A description of some of the similar elements and features are omitted to reduce redundancy. 
     As shown in  FIGS.  133 A- 133 B , the snap  13300  includes a single-piece or integrally formed male assembly  13320  and a single-piece or integrally formed female assembly  13330 . The snap  13300  also includes partially molded end caps  13340  and  13350  that define exterior surfaces of the snap  13300  and that are attached to the male assembly  13320  and female assembly  13330 , respectively. Similar to examples previously described, the snap  13300  is configured to couple a first element  13310  to a second element  13312 , which may be two elements or regions of an accessory, as described previously. 
     As shown in  FIGS.  133 A- 133 B , the male assembly  13320  includes an internal pocket or recess for receiving a first magnetic element  13322 . In this example, the first magnetic element  13322  is positioned within the protrusion or protruding portion of the male assembly  13320 . Similarly, the female assembly  13330  includes an internal pocket or recess for receiving a second magnetic element  13332  that is positioned below a surface that defines a bottom of the recess of the female assembly  13330 . The first magnetic element  13322  and the second magnetic element  13332  are arranged with opposite poles facing each other such that the first and second magnetic elements  13322 ,  13332  are magnetically attracted to each other. As shown in  FIG.  133 A , the first and second magnetic elements  13322 ,  13332  are positioned sufficiently close that the attractive magnetic forces are sufficiently strong to maintain the engagement between the male and female assemblies  13320 ,  13330  of the snap  13300 . In this way, the first and second magnetic elements  13322 ,  13332  provide the engagement force that holds the snap  13300  in the close position in order to couple the first element  13310  to the second element  13312 . 
     The snap also includes compliant members  13324  and  13334  that are positioned behind respective magnetic elements  13322 ,  13332  in order to reduce rattling or other undesirable effects. As shown in  FIGS.  133 A- 133 B , the compliant member  13324  is positioned between the first magnetic element  13322  and an inner surface of the first cap  13340 . The compliant member  13324  may be formed from a compressible foam or other similar material. The compliant member  13324  may be slightly compressed and exert a retaining force on the first magnetic element  13322 , which may help maintain the position of the first magnetic element  13322  and prevent undesired rattling or vibration. Similarly, the other compliant member  13334  is positioned between the second magnetic element  13332  and an inner surface of the first cap  13350 . The other compliant member  13334  may also be formed from a compressible material and may be slightly compressed and exert a retaining force on the second magnetic element  13332 . In some implementations, the compliant members  13324 ,  13334  and/or the magnetic elements  13322 ,  13332  may be glued or adhered to an inner surface of the snap  13300  to reduce vibration or other undesirable effects. 
     The materials of the snap  13300  may be similar to the other example provided herein. In particular, the unitary pieces that form the male assembly  13320  and the female assembly  13330  may be a stamped stainless steel material or other metal alloy that allows for the magnetic coupling between the first and second magnetic elements  13322 ,  13332 . 
     As discussed herein, the wireless tag may have a variety of features and functions that have a broad applicability and a large number of use cases. As described in more detail below with respect to  FIGS.  69 A- 128   , a wireless tag module, also referred to herein as a wireless module, may be physically integrated with an accessory of another device, also referred to herein as a base device. In particular, a wireless module may establish a wireless connection with the base device and expand the functionality of that device by allowing access to various hardware elements of the wireless module over the wireless connection. This allows aspects of the wireless tag to be integrated with the base device in order to expand the functionality of that device and provide an expanded feature set without having to modify or significantly impact the hardware of the base device. 
       FIGS.  134 A- 134 C and  135 A- 135 C  depict example wireless tags or wireless modules integrated with an accessory of a base device. In particular,  FIGS.  134 A- 134 C and  135 A- 135 C  depict a wireless module that is integrated into a band accessory of a smart watch or other wrist-worn device. While the following examples are provided with respect to a wireless module that is integrated with a band accessory, the same or a similar wireless module may be integrated into another accessory, like a case, cover, lanyard, frame, docking station, and the like. Further, while the following examples are provided with respect to a watch or other wrist-worn device, many of the functions and principles described may also be applied to a variety of other base devices including, for example, a smart phone, tablet computer, digital media player, health monitoring device, laptop computing system, desktop computing system, and so on. 
       FIGS.  134 A- 134 C  depict an example wireless module or wireless tag that is integrated into a band of a smart watch or other wearable device. In particular,  FIGS.  134 A- 134 C  depict a wireless tag, referred to herein as a wireless module  13400  that is attached or otherwise integrated with a band  13402  of a watch  13405 . For ease of discussion, in the following examples, the watch  13405  includes a watch body  13404  that may be separate from the band  13402  A watch body  13404  without a band may also be referred to herein as a watch base or simply a watch. The watch  13405 , as used herein, may be described as the complete electronic device that includes the watch body  13404  and the band  13402 , which may in turn include the wireless module  13400 . The watch body  13404  of the (smart) watch  13405 , also referred to herein as a base device, includes a display  13406  for producing graphical output and various internal components including, for example, a processor, a wireless communication circuit, an input device, a battery, one or more sensors, and other electronic components. The wireless communication circuit of the watch body  13404  may be configured to transmit and receive wireless communication signals, in accordance with the embodiments described herein. The display  13406  may include a liquid crystal display (LCD) element, organic light emitting diode (OLED) display element, or other type of display element. The display  13406  may also include a touch and/or force sensor that is configured to detect a touch and/or force applied to a cover over the display  13406 . In some instances, a touch-sensitive display or force-sensitive display may also be referred to as a touchscreen. As shown in  FIG.  134 A , the watch body  13404  may also include one or more buttons, dials, crowns, switches, or other mechanically actuated input devices. For purposes of the following description, these mechanically actuated input devices are generally referred to as a button  13408 . 
     The watch body  13404 , as an example base device, also includes a variety of other elements, components, and subsystems. A description of an example base device is provided below with respect to the electronic device  14000  of  FIG.  140   . In the following examples, the base device is a watch  13405  or watch body  13404  and the accessory is a band  13402 . However, in other implementations, the base device may be another electronic device like a mobile phone, tablet computing device, portable media player, health monitoring device, or other type of electronic device. Likewise, in other implementations, the accessory may be a cover for the electronic device, a protective case for the electronic device, a charging station for the electronic device, or other type of accessory for the electronic device. Similar to as described below with respect to the band  13402 , a wireless module  13400  may be installed or otherwise integrated with an accessory (e.g., a cover, protective case, charging station) by installing the wireless module  13400  in a hole, recess, or opening of the respective accessory. In some cases, the wireless module  13400  is integrated into the accessory through a molding technique, mechanical fastener technique, welding technique, or other integration technique. 
     The wireless module  13400  includes a wireless communication system, including a wireless communication circuit and antenna for wirelessly transmitting and receiving signals from a separate device. In this example, the wireless module  13400  includes a wireless communication system that is configured to operably connect or couple to the wireless communication system of the base device, which, in this case, is a smart watch  13405  or watch base  13404 . The wireless link between the wireless module  13400  and the watch body  13404  may be automatically established when the band  13402  is installed or physically attached to the watch body  13404 . The wireless link may be established in response to a sensor in the watch body  13404  detecting the presence of the band  13402  and/or through a manual setting provided by the user. In some cases, the wireless link may be established by determining that one or more of the respective internal sensors of the wireless module  13400  and the watch body  13404  are providing an output that indicates that the wireless module  13400  is coupled to the watch body  13404  by the band  13402 . For example, accelerometer output, gyro sensor output, UWB sensing system output, GPS output, or other sensing system output may be used to determine if movement of the wireless module  13400  corresponds to movement of the watch body  13404  in a way that indicates that the devices are physically coupled. 
     Using the wireless communication link, sensor signals or data from the wireless module  13400  may be passed to the watch body  13404 . As described herein, the sensor signals or data from the wireless module  13400  may be transmitted to the watch body  13404  as a wireless input signal, which is received by a corresponding wireless circuit of the watch body  13404 . The display  13406  of the watch body  13404  may be responsive to the wireless input signal received from the wireless module  13400 . By way of example, the wireless module  13400  may include a button or other input device that may be actuated in response to a user touch or finger press. As described in more detail below, the wireless module  13400  may include an electromechanical switch, capacitive touch sensor, force sensor, or other similar type of input device. In some cases, the wireless module  13400  includes an array of capacitive nodes or electrodes that are configured to determine a location of a touch, a gesture input, and/or a direction or path of a touch&#39;s movement on the surface of the wireless module  13400 . The watch body  13404  may be responsive to an actuation of the input device on the wireless module  13400 , which may be used to perform one or more of a variety of functions. By way of example, the watch body  13404  may be responsive to the input device in order to wake the watch body  13404 , place the watch body  13404  in a sleep or hibernation mode, acknowledge receipt of an incoming message, silence an alarm or other output of the watch body  13404 , initiate a payment for an electronic transaction, access a list of contacts or an address book on the watch body  13404 , display a list of programs or apps running on the watch body  13404 , access a previous screen or display of the graphical user interface displayed on the display  13406  of the watch body  13404 , start or stop a stopwatch or other timing function of the watch  13404 , initiate a running or activity tracking program or function of the watch body  13404 , initiate or begin playing a song or other media for a media-player function of the watch body  13404 , and/or perform another function on the watch body  13404 . In some cases, the wireless module  13400  and/or the watch body  13404  may be programmable to replicate the functionality of one or more buttons  13408  of the watch body  13404 . Similarly, the wireless module  13400  and/or the watch body  13404  may be programmable to replicate functionality of the touch- and/or force-sensitive surface of the display  13406  (e.g., the touchscreen). For example, an input provided to the wireless module  13400  may be used as a supplement to or replacement for a touch and/or force input on the display  13406 . The wireless module  13400  may, for example, be configured to detect gesture or other dynamic touch input using a capacitive array of nodes or electrodes. The gesture and/or dynamic input may be used to replicate touch and gesture input that may be provided to the touch screen display. A touch, gesture, and/or force input to the wireless module  13400  may be used to select a graphical object displayed on the display  13406 , change a display mode of the graphical user interface, actuate a virtual button displayed in the display  13406 , scroll through a list of items on the display, perform a zoom function on the display, enter a passcode or signature gesture, or perform other functionality on the watch body  13404 . 
     Using the wireless communication link, signals and/or data from the watch body  13404  may also be passed to the wireless module  13400  using a wireless input signal, wireless output signal, or other type of wireless signal. The wireless module  13400  may be responsive to such signals and/or data from the watch body  13404  and may be configured to perform one of a variety of functions or outputs in response to operations performed on the watch body  13404 . In one example, the wireless module  13400  includes a haptic device or other device that is configured to produce a haptic output that is tactilely perceptible to the user. For example, the wireless module  13400  may include an electromagnetic or piezoelectric haptic engine that is configured to produce a vibration or other haptic output along an exterior surface of the wireless module  13400  that is likely to contact the user&#39;s skin. In this example, the wireless module  13400  may be configured to produce a haptic output along an inner surface of the wireless module  13400  that is likely to contact the user&#39;s wrist. The wireless module  13400  may also be configured to produce an acoustic or audio output using a speaker or other acoustic device in response to signals and/or data received from the watch body  13404 . The wireless module  13400  may also include a display, light-emitting element (e.g., an LED), or other visual output device that is configured to produce a visual output in response to a signal received from the watch body  13404  and/or an internally generated command or instruction. For example, the wireless module  13400  may include a LED, array of LEDs, and/or a segmented display that is responsive to a signal received from the watch body  13404  and/or an internally generated command or instruction. 
     The wireless module  13400  may be responsive to activity on the watch body  13404  and produce an acoustic and/or haptic output in response to one or more of a variety of operational scenarios. For example, the wireless module  13400  may produce a haptic output, acoustic output, and/or visual output in response to: an alert or alarm initiated by the watch body  13404 , a message received by the watch body  13404 , or a selection of a graphical object on the display  13406  or touchscreen of the watch body  13404 . 
     The wireless module  13400  may also be adapted to operate in concert with one or more subsystems operating on the watch body  13404 . For example, the wireless module  13400  may provide a supplemental antenna or function as a wireless receiver for the watch body  13404 . The wireless module  13400  may also include location-determining hardware like a global positioning system (GPS) sensor or the like and the wireless module  13400  may relay data and/or signals to the watch body  13404  to provide location information that may be used to determine the location of the user and/or supplement location-determining hardware that is incorporated into the watch body  13404 . In accordance with other embodiments described herein, the wireless module  13400  may also include a wireless locating system (e.g., a UWB wireless system) that may be adapted to determine a relative and/or absolute location of the wireless module  13400  using one or more of the techniques described herein with respect to other example wirelessly locatable tags. Additionally or alternatively, the wireless module  13400  may include a wireless locating system, which may be used alone or in concert with one or more antennas of the watch body  13404  in order to improve accuracy of location-determining functionality of the watch body  13404 . Similarly, the wireless module  13400  may also include one or more accelerometers, gyro sensors, magnetometers, or other sensors that may operate in coordination with one or more similar sensors incorporated into the watch body  13404  in order to improve a determination of device location, device orientation, user activity, user posture, or other similar functions. An example of the various hardware elements that may be included in the wireless module  13400  is described below with respect to  FIG.  144   . 
     As shown in  FIG.  134 B , the wireless module  13400  is positioned within a hole or opening  13403  of the band  13402 . As shown in  FIG.  134 B , the wireless module  13400  includes an enclosure  13420  that is defined by an upper housing  13422  that is coupled to a lower housing  13424 . The enclosure  13420  encloses a circuit assembly  13426  and a battery  13428  that is operably coupled to the circuit assembly  13426 . The various components may be similar to the components described herein with respect to other wireless tag embodiments. A redundant description of the various shared components is omitted to reduce redundancy and improve clarity. 
       FIG.  134 C  depicts an example cross-sectional view of the wireless module  13400  taken along section  134 C- 134 C of  FIG.  134 A . As shown in  FIG.  134 C , the wireless module is retained within the opening  13403  of the band  13402  by a pair of flanges. An upper flange  13440  is defined along a periphery of the upper housing  13422  and a lower flange is similarly defined along a periphery of the lower housing  13424 . A portion of the band  13402  is trapped between the upper flange  13440  and the lower flange  13442  thereby retaining the wireless module  13400  within the opening  13403  of the band  13402 . As shown in  FIG.  134 C , the opening  13403  of the band  13402  may include a counter bore on either side to help nest the respective flanges  13440 ,  13442  within the profile of the band  13402 . In some implementations, the bottom surface defined by the lower housing  13424  is substantially aligned or coplanar with a surface of the band  13402 , which may reduce the tactile perception of the wireless module  13400  by the user when the watch  13405  is being worn. In the present example, an outer surface defined by the upper housing  13422  is aligned with an outer surface of the band  13402  along a periphery of the wireless module  13400  but protrudes or is proud of the outer surface of the band  13402  along a central or middle portion that is surrounded by the periphery. This may allow the user to locate the button of the wireless module  13400  by touch or with minimal visual cues. The band  13402  may be formed from any one of a variety of materials including, for example, silicone, fluoropolymer, nylon, or another type of polymer material. In some cases, one or both of the upper housing  13422  or the lower housing  13424  may include one or more materials that are in common with the material of the band  13402  in order to provide a uniform appearance and/or tactile feel. 
     The lower housing  13424  and the upper housing  13422  may be formed from similar materials as other wireless tag embodiments described herein. In particular, the lower housing  13424  may be formed from a metal, polymer, and/or composite material and may include one or more latches or catches that engage a respective mating feature of the upper housing  13422 . In some cases, the lower housing  13424  is configured to be removable by a user in order to replace the battery  13428  or other internal components. Various removable doors and housing components are described with respect to other embodiments herein and not repeated with respect to this example to reduce redundancy. 
     As shown in  FIG.  134 C , the wireless module  13400  includes an electromechanical switch  13430  that may be actuated with a finger press along the exterior of the enclosure  13420 . In this example, the switch  13430  is a compressible tactile dome that buckles or collapses in response to an external press or force in order to close an electrical contact or produce another electrical response. The compressible tactile dome may also be referred to herein as a “tactile dome switch.” In some cases, a capacitive touch sensor, a force sensor, or other type of sensor may be used to detect a press or touch of a finger. As described previously with respect to other embodiments herein, the upper housing  13422  may be configured to locally deflect or displace in response to a touch or press by a finger. In particular, an outer portion of the upper housing  13422  may be formed from a compliant or flexible material in order to allow the middle or central portion to deflect or displace in response to a touch or press. Portions of the upper housing may be formed from a silicone material, synthetic rubber, or other compliant material that allows for a deformation of the upper housing in response to a touch. In some cases, the movement of the upper housing  13422  and/or the movement of the compressible tactile dome of the switch  13430  provides a haptic or tactile output that indicates that the switch  13430  has been actuated. The haptic or tactile output may be a click or other similar tactile response. In some cases, the wireless module  13400  includes a separate haptic device that produces the haptic or tactile feedback in response to a touch or press. 
     In this way, the wireless module  13400  may function as a remote button or additional input device for the watch  13405 . As described previously, the watch body  13404  may be responsive to an actuation of the switch  13430  and perform one or more of the functions described above. One benefit to the use of a wireless module  13400  is that additional buttons or input devices may be added to the watch body  13404 , which may have limited area for additional buttons or input devices. As discussed above, the wireless module  13400  may also include one or more electronic sensors that may be used to help determine the location and/or orientation of the watch body  13404 , and/or help determine a user activity or position. 
     The additional functionality enabled by the wireless module  13400  can be provided without having to substantially modify or alter the hardware of the watch body  13404 . In the embodiment of  FIGS.  134 A- 134 C , the wireless module  13400  does not include a conductive electrical connection to the watch body  13404  and, instead, is electrically coupled to the watch body  13404  by a wireless communication link. This allows for the functionality of the wireless module  13400  to be added or removed by merely swapping the band that is attached to the watch body  13404 . 
     In some cases, a band may include multiple wireless modules in order to provide additional user input devices and/or sensors. As depicted in  FIGS.  134 A- 134 B , the watch  13405  may include multiple wireless modules  13400 ,  13401  that are located along different regions of the band  13402 . The additional wireless module  13401  may operate in a substantially similar way and include similar elements and components as described herein with respect to wireless module  13400 . In some implementations the wireless modules  13400  and  13401  are configured differently or have different hardware arrangements. While only two wireless modules  13400 ,  13401  are depicted in  FIGS.  134 A- 134 B , other implementations may include more than two modules. In some cases, an array of three or more modules may be arranged along the length of the band  13402 , each module configured to operate using at least some of the functionality described herein with respect to wireless module  13400 . 
     As shown in  FIG.  134 C , the wireless module  13400  is electrically isolated from the watch body  13404  and includes a separate battery  13428  for a power source. The battery  13428  may be replaceable and/or rechargeable by an external power source. In the current implementation, the wireless module  13400  includes a wireless charging coil  13436  that may be configured to receive power wirelessly from an external charging coil in a separate charging dock or charging device. As described previously, the external charging coil may be configured to produce an electromagnetic field that induces a current in the charging coil  13436 , which may be used to supply (wireless) power to the wireless module  13400  and charge the battery  13428 . 
     As shown in  FIG.  134 C , the wireless module  13400  may also include one or more magnetic elements  13432  that may be used to secure or locate the wireless module  13400  with respect to an external charging device, which may also include a mating magnetic element that is configured to magnetically couple with the magnetic element  13432  while the wireless module  13400  is docked to the external charging device. In some instances, the protruding shape or convex profile of the upper housing  13422  may also help to locate the wireless module  13400  with respect to an external charging device. In some embodiments, the external charging device is configured to wirelessly charge both the wireless module  13400  and the watch body  13404  in a common dock that includes external wireless charging coils for both the wireless module  13400  and the watch body  13404 , which may be housed or enclosed by an common dock enclosure or housing. 
     As shown in  FIGS.  134 B- 134 C , the wireless module includes a circuit assembly  13426  that is operably coupled to the battery  13428  and the switch  13430 . The circuit assembly  13426  includes wireless communication circuitry (wireless circuitry) that is operably coupled to or includes an antenna. As described previously, the wireless communication circuitry may be configured to establish and maintain a wireless communication link with the watch body  13404 . The wireless communication link may be conducted in accordance with an established wireless communication protocol including, for example, Bluetooth, BLE, WiFi, or another protocol. The wireless communication link may be established automatically based on a determination that the wireless module  13400  and band  13402  are attached to the watch body  13404 . 
     The wireless communication circuitry may also be configured to communicate with external devices using the same protocol or another separate protocol. As described previously with respect to other wirelessly locatable tags described herein, the wireless module  13400  may have wireless communication circuitry that may be used to locate the wireless module  13400  (and thus also locate the base device—the watch  13405  or watch body  13404 ). In some cases, the wireless communication circuitry may be configured to generate or relay location data that may be used as part of a mesh or ad-hoc network of devices. Similar to as described above with respect to the other wirelessly locatable tag embodiments, the wireless module  13400  may be used to securely transmit location information about itself or another device using a digital key or other authentication technique. As such, the functionality of the wirelessly locatable tag, as described herein, may be added to a device by incorporating a wireless module  13400  into an accessory of the device. Because the wireless module  13400  includes a separate power supply (battery  13428 ) and circuit assembly  13426 , the wireless module  13400  may operate independent of the base or host device while also being used to locate the base or host device (e.g., watch  13405  or watch body  13404 ) using one or more of the techniques described herein. 
     As discussed previously, the circuit assembly  13426  may also include one or more sensors including, without limitation, an accelerometer, gyro sensor, magnetometer, GPS sensor, or other similar type of sensor that may be used to track the location, orientation, and/or movement of the wireless module  13400 . The circuit assembly  13426  may also include a microphone, speaker, or other audio component for producing an audio output and/or receiving an audio input. In some instances, the circuit assembly  13426  also includes one or more antennas, which may be used for wireless communication and or location using a UWB, time of flight, or other similar technique. The circuit assembly  13426  may also include one or more processors or processing units that are configured to execute instructions, software, firmware, code or other computer-executable instructions. 
     The circuit assembly  13426  may also include a near-field communication (NFC) circuit and antenna for wirelessly coupling to another device that is proximate to the wireless module  13400 . In some cases, the NFC antenna is integrated with the wireless charging coil  13436 . In some cases, the NFC antenna is a separate element or component that is electrically and/or structurally coupled with the circuit assembly  13426 . In some cases, the NFC antenna is formed on or otherwise integrated into the circuit assembly  13426 . 
     The wireless module  13400  may also include a display element and/or other visual output device. The display element may include a segmented display, LCD, OLED or other type of display element. In some cases, the circuit assembly  13426  includes one or more LEDs or other visual output devices that may provide a visual output along a surface of the wireless module  13400 . The wireless modules  13400  may include one or more covers, light guides, light pipes, or other elements that enable the visual output of the display element and/or another visual output device. 
     As shown in  FIGS.  134 A- 134 C , the wireless module  13400  is incorporated into a band  13402  of the watch  13405 . However, the wireless module  13400  may also be incorporated into another accessory or device that may be paired with the watch. The accessory or device may be manufactured by a third party and may include additional electronic components that are configured to provide a particular set of functions. The wireless module  13400  may function as the wireless connection or bridge between the third-party or external device and the base device (watch body  13404 ). The third party or external device may be configured to transmit signals and/or data to the wireless module  13400  using an advanced programming interface (API) or other communication protocol. Signals and/or data transmitted to the wireless module  13400  may then be passed on to the base device (watch body  13404 ) using the wireless communication link established between the wireless module  13400  and the base device (watch body  13404 ). Using the wireless module  13400  as an intermediary between devices allows accessories, third-party devices or other external devices to establish one uniform interface with the wireless module  13400 . The wireless module  13400  may then be adapted to work with a range or variety of base devices without having to reprogram or reconfigure the accessory, third-party device, or other external device. For example, an accessory may access or provide signals and/or data to a first base device (e.g., a watch body  13404 ) using a wireless module (e.g., wireless module  13400 ) and also access a second base device (e.g., a phone or tablet) using another wireless module having a similar API or other protocol as the wireless module  13400 . 
     One example implementation may involve an integration of a separate heart-rate monitor that may be worn or otherwise coupled to a user in order to track and monitor a biological function or biometric of the user, like a heart rate. The heart rate monitor may include a sensor, a processor, and a wireless communication system that has been adapted or configured to wirelessly interface with a wireless module (similar to the wireless module  13400 ). For purposes of this example, the heart rate monitor may be characterized as an accessory, third-party device, or an external device and may produce a signal or data that corresponds to the measured biometric (e.g., a heart rate). The signal or data (first signal or first data) may be transmitted from the heart-rate monitor to the wireless module using a first wireless communication link (which may implement a first protocol or set of APIs). The wireless module may then relay a second signal or second data (that is based on the first signal or first data) to the base device using a second wireless communication link (which may implement a second protocol or set of APIs). The base device may display information related to the measurement of the biodata as part of a health monitoring software program or graphical user interface. Similarly, the wireless module may be used to pass signals or data from the base device to the heart rate monitor, which may include commands to initiate a measurement, stop a measurement, enter a designated power state, or other type of command or signal. Using the wireless module, the heart rate monitor may interface with a variety of base devices (e.g., a watch, a mobile phone, a tablet computing system) through a respective wireless module, without having to substantially alter a wireless interface or protocol. As a result, any base device having a suitably coupled wireless module may be used with the heart-rate monitor. A similar scheme may be used to couple a variety of external devices with a base device using a wireless module, as described herein. Example external devices include, without limitation, wireless speakers, wireless headsets, bar-code scanners, navigation systems, automobiles, home security systems, doorbell systems, thermostats, appliances, home automation systems, and the like. 
       FIGS.  135 A- 135 C  depict another example of a wireless tag or module that is integrated with an accessory of a device. More specifically,  FIGS.  135 A- 135 C  depict another example of a wireless tag also referred to as a wireless module  13500  that is integrated with a watch band  13502  of a watch  13504 . Similar to the previous example, the watch  13504  is referred to separately from the band  13502 . However, the watch  13504  may also be described as including the band  13502  and, in some cases, the wireless module  13500 . The smart watch or simply watch  13504 , also referred to herein as a base device, includes a display  13506  for producing graphical output and various internal components including, for example, a processor, a wireless communication module, an input device, a battery, one or more sensors, and other electronic components. The display  13506  may be similar to the display  13406  described above and may include one or more display elements, a touch sensor, force sensor, and other similar elements. The watch  13504  may also include one or more buttons, dials, crowns or other input devices represented by the button  13508  depicted in  FIG.  135 A . The watch  13504  is an example base device and may include various components that are not expressly depicted in  FIGS.  135 A- 135 C . 
     The wireless module  13500  may be configured to wirelessly pair or connect to the watch  13504  in a similar fashion as described above with respect to  FIGS.  134 A- 134 C . Similar to the previous example described above, the wireless module  13500  may be used to enhance the functionality of the watch  13504  without substantially modifying or altering the hardware of the watch  13504 . The wireless module  13500  may operate in a substantially similar fashion as wireless module  13400 , described above. A description of the shared features and functionality is omitted from the description to reduce redundancy. 
     The wireless module  13500  includes many of the same components and functional elements as described above with respect to the wireless module  13400 . An example of the various hardware elements that may be included in the wireless module  13500  is described below with respect to  FIG.  144   . However, as shown in  FIG.  135 B , the wireless module  13500  provides for a remote switch  13530  with may be operably and electrically coupled to the circuit assembly  13526  by a flexible circuit  13532 . The flexible circuit  13532  may include an array of conductive traces that are formed on a dielectric material that may be able to be reliably flexed or bent with normal use of the band  13502 . While the present example depicts a single switch  13530 , an alternative embodiment may include multiple switches that may be located along the length of the band  13502 . 
     By decoupling the switch  13530  from the other elements of the wireless module  13500 , the functionality may be expanded without substantially altering the main components of the wireless module  13500 . This may allow for a variety of watch band configurations having specialized or dedicated buttons that are adapted for a particular use case or functionality. For example, the wireless module  13500  may be integrated with a sports band and include multiple switches or buttons, each switch or button dedicated to a stopwatch function, fitness tracking function, or other similar sports-related function. By way of further example, the wireless module  13500  may be adapted for underwater use or for use while swimming. Due to the presence of water, the touch functionality of the touch screen display  13506  may not operate consistently or where gloves may impede the operation of a capacitive touch sensor. Key functionality or operations of the watch  13504  may be mapped to the one or more switches of the wireless module  13500  in order to allow for use when the device is wet or when a capacitive touch sensor may not be operable. 
     As shown in  FIG.  135 B , the circuit assembly  13526  may be enclosed and sealed using a set of components that together define the enclosure  13520  of the wireless module  13500 . Specifically, the enclosure  13520  includes an upper housing  13522  that defines an outer or upper surface of the wireless module  13500 . In this example, the upper housing  13522  includes a prong  13523  or other similar feature that may be used as a clasp or fastener for the band  13502 . The prong  13523  may be configured to be inserted into and retained by a corresponding hole in a strap of the band  13502  to form a clasp or securing fastener to secure the band  13502  to the user. In this example, the prong  13523  is integrally formed with the upper housing  13522  and includes a catch or lobe at the end of the prong  13523  that is configured to engage a hole in a strap or other element of the band  13502  in order to secure the band  13502  around the wrist of a user. The enclosure also includes a lower housing  13524  that defines an inner or lower surface of the wireless module  13500 . The lower housing  13524  may be removable to allow for replacement or servicing of the battery  13528 . An O-ring  13562  or other type of seal may be used to form a water-proof or water-resistant seal between the lower housing  13524  and the rest of the enclosure  13520 . 
     The enclosure  13520  also includes a central ring  13550  that is positioned between the upper housing  13522  and the lower housing  13524 . The central ring  13550  may be used to mount the circuit assembly  13526  and may help secure the wireless module  13500  to the band  13502 . As shown in  FIG.  135 B , the enclosure  13520  may include adhesive rings  13564 ,  13566  that form a seal between the central ring  13550  and the lower housing  13524  and the upper housing  13522 , respectively. In some cases, the adhesive rings  13564 ,  13566  are formed from a heat-activated adhesive layer, a pressure-sensitive adhesive layer, or another type of adhesive layer or seal. In some implementations, the central ring  13550  includes threaded features that are configured to engage with either or both of the lower housing  13524  and the upper housing  13522 . 
       FIG.  135 C  depicts a cross-sectional view of the wireless module  13500  along section  135 C- 135 C of  FIG.  135 A . As shown in  FIG.  135 C , the wireless module  13500  is retained within the band  13502  by a retaining ring  13552 . The retaining ring  13552  may be formed from a polymer or metal material that is inserted into a groove in an opening in the band  13502 . In some cases, the band  13502  is molded around the retaining ring  13552 . In other cases, the retaining ring  13552  is installed into the groove after the band  13502  has been molded or otherwise formed. As shown in  FIG.  135 C , the enclosure  13520  of the wireless module engages the retaining ring  13552  by an upper flange  13540  formed into the upper housing  13522  and the central ring  13550 . The lower housing  13524  also includes a lower flange  13542  that is configured to seat or contact against a surface of the central ring  13550 . 
       FIG.  135 C  also depicts a cross-sectional view of the switch  13530 , which is positioned below a membrane, cover layer, or outer layer  13503  that defines an outer or exterior surface of the band  13502 . The outer layer  13503  may be formed from a material that is similar to the main strap of the band  13502 . In some cases, the outer layer  13503  is formed from silicone, fluoropolymer, nylon, or another type of polymer material. Similar to the previous example, the switch may include a tactile dome that forms an electrical switch that is closed or otherwise provides an electrical response in response to an applied force or touch, as indicated by the arrow. The tactile dome of the switch  13530  (also referred to as a “tactile dome switch”) may be attached to a surface of the flexible circuit  13532 , which operably and electrically couples the switch  13530  to the circuit assembly  13526 . 
     As described herein, a wireless tag may be useful for a variety of applications. As described below with respect to  FIGS.  136 A- 136 C,  137 A- 137 B,  138 A- 138 B, and  139   , an array of wireless tags may be used to track and/or monitor a user&#39;s posture. In general, poor posture may be a major contributor to chronic back pain and other musculoskeletal issues. As many as two thirds of adults experience lower back pain at some point in their lives and incorrect posture may be a significant cause. Lower back pain may also be a significant cause of workplace-related disabilities and may result in reduced productivity and quality of life. However, lower back pain and other musculoskeletal issues may be improved or prevented through consistent posture monitoring and posture correction. As described below with respect to  FIGS.  136 A- 136 C,  137 A- 137 B,  138 A- 138 B, and  139   , wireless tags may be strategically positioned along a body of a user and used to monitor and correct potentially problematic posture issues to help avoid chronic physical ailments. 
     An array of wirelessly locatable tags (also referred to herein as “wireless tags” or simply “tags”) may be positioned or fixed with respect to various regions along a user&#39;s body in order to track and monitor a user&#39;s posture. As shown in  FIG.  136 A , a posture-monitoring system  13601  may include an array of wireless tags  13600   a - 13600   f  that are positioned along various locations of a user&#39;s back. As previously discussed, a location of a wireless tag may be determined relative to another device using wireless location-tracking techniques including, for example, time of flight (ToF), angle of arrival (AoA), time difference of arrival (TDOA) received signal strength indication (RSSI), triangulation, synthetic aperture, and/or any other similar techniques. The wireless tag may be used to determine a relative location or distance with respect to another external device or wireless tag. The wireless tag, in some implementations, may be used to determine an absolute location or position by using a global positioning system (GPS) or other locating system that is either integrated with the wireless tag or integrated with a separate device. 
     As shown in  FIG.  136 A , a posture-monitoring system  13601  may include an electronic device  13610  and an array of wireless tags  13600   a - 13600   f  that are either directly attached to a user  13605 , incorporated into an article of clothing, or otherwise coupled to the user  13605  at various positions along the user&#39;s body. The electronic device  13610  may be a mobile telephone, portable computer, tablet computer, portable music player, or other portable electronic device. The electronic device  13610  may also be attached to the user and may be a watch, a smart watch, a wrist-worn health monitoring device, or other type of wearable electronic device. The electronic device  13610  may also be a notebook or laptop computer system, a desktop computer system, health monitor device, or other type of device. An example electronic device  14300  is described below with respect to  FIG.  143   , a complete description which is not repeated here for electronic device  13610 . In some cases, the electronic device  13610  is an appliance or other device that is fixed in a room or location. While only one electronic device  13610  is depicted in the example system,  13601  of  FIG.  136 A , other implementations or systems may include multiple electronic devices, which may improve the accuracy and/or reliability of the posture tracking system. 
     As shown in  FIG.  136 A , each wireless tag  13600   a - 13600   f  is positioned at a different location along the body of the user  13605 . Specifically, the wireless tags  13600   a  and  13600   b  are positioned along shoulder regions of the user  13605 , wireless tag  13600   c  is positioned along a mid-back region of the user  13605 , wireless tag  13600   d  is positioned along a lumbar region of the user  13605 , and wireless tags  13600   e  and  13600   f  are positioned along a leg (e.g., a knee region) of the user  13605 . The configuration and position of the wireless tags  13600   a - 13600   f  is provided by way of an example illustration and the number and locations of the various wireless tags may vary depending on the implementation. 
     Each of the wireless tags  13600   a - 13600   f  is configured to use a wireless-location technology to determine a relative location with respect to one or more of the other wireless tags  13600   a - 13600   f . In one implementation, each of the wireless tags  13600   a - 13600   f  is configured to use a respective UWB signal to determine a relative location of the respective wireless tag  13600   a - 13600   f  with respect to the electronic device  13610 , also referred to herein as a base device, host device, or a reference device. As described previously, each of the wireless tags  13600   a - 13600   f  may be able to determine a relative distance to the electronic device  13610  using a time of flight (ToF), angle of arrival (AoA), time difference of arrival (TDOA) received signal strength indication (RSSI), triangulation, synthetic aperture, and/or any other similar techniques, one or more of which may be implemented using a UWB wireless system. The location and/or position information determined using each of the wireless tags  13600   a - 13600   f  may be transmitted to the electronic device  13610  as what may be referred to herein as a (wireless) locating signal. The wireless locating signal may include location data that corresponds to a distance between the respective wireless tag  13600   a - 13600   f  and the electronic device  13610  or another reference. In some cases, the wireless locating signal includes a UWB wireless pulse that is used to measure the relative distance using one or more of the aforementioned techniques. In other cases, the wireless locating signal may include locating data that includes a relative location or distance between tags or devices. In this case, the wireless locating signal may be transmitted using a wireless protocol that is different than a UWB pulse that is used to determine the relative location or distance. For example, the wireless locating data may be transmitted using a Bluetooth, WiFi, or other wireless transmission protocol. 
     The electronic device  13610  may be adapted to coordinate the various wireless locating signals to determine a relative location of each of the wireless tags  13600   a - 13600   f . In some implementations, the electronic device  13610  may be able to determine an absolute location using a GPS signal or other absolute location determining technique, which may be used to determine an absolute and/or relative location of each of the wireless tags  13600   a - 13600   f . In some implementations, a magnetometer and or accelerometer of the electronic device  13610  is used to determine a relative and/or absolute location of the wireless tags  13600   a - 13600   f.    
     In some implementations, the wireless tags  13600   a - 13600   f  are configured to determine an estimated distance between each of the wireless tags  13600   a - 13600   f  without the use of an external electronic device  13610 . For example, each of the wireless tags  13600   a - 13600   f  may be configured to operate as either a transmitter or a receiver in a time-of-flight or other wireless measurement scheme in order to determine a distance between a pair of wireless tags  13600   a - 13600   f . In such embodiments, the wireless locating signal may comprise an estimate of a distance between one or more other wireless tags  13600   a - 13600   f . In some cases, each of the wireless tags  13600   a - 13600   f  includes an accelerometer, magnetometer, or other element that is configured to determine a device orientation, which may be used to determine a relative location of each of the wireless tags  13600   a - 13600   f . In some cases, the accelerometer, magnetometer, or other element that is configured to determine a device orientation provides additional information about the position of the user&#39;s body including torso or shoulder twist. 
     In some implementations, the wireless tags  13600   a - 13600   f  may be configured to use a grid or network of other wireless tags that are not attached to the user  13605  in order to determine a relative location of each of the wireless tags  13600   a - 13600   f . Also, as suggested above, the wireless tags  13600   a - 13600   f  may be adapted to use multiple (external) electronic devices to determine a relative location. For example, three electronic devices may be used to “triangulate” multiple UWB signals and determine a relative location of each of the wireless tags  13600   a - 13600   f.    
     The position and/or posture of the user  13605  may be monitored using the relative or absolute location of each of the wireless tags  13600   a - 13600   f . The position of the user  13605  in  FIG.  136 B  may represent a nominal or an ideal posture position. As shown in  FIG.  136 B , an ideal goal location of each of the wireless tags  13600   a - 13600   f  may be determined with respect to a datum or reference, here represented by the reference plane  13604  depicted in  FIG.  136 B . The location of the reference plane  13604 , in this example, may be determined as a vertical plane that is positioned with respect to the wireless tags  13600   a ,  13600   b  located along the shoulder regions of the user  13605 . A nominal position of each of the other wireless tags  13600   c - 13600   f  may be specified in terms of a reference offset or delta with respect to the reference plane  13604 . The reference offset of each of the wireless tags  13600   a - 13600   f  may be determined on a user-by-user basis as each user&#39;s body is unique and the nominal, normal, or ideal position of the wireless tags  13600   a - 13600   f  may vary from user-to-user depending on muscle mass, body fat content, and other physical body features. Other techniques may also be used to determine the reference or ideal position of the wireless tags  13600   a - 13600   f  including, for example, local coordinate values with respect to a datum origin, working envelopes, or other spatial constraining techniques. Reference or ideal position data may be stored in computer-readable memory for use by the posture-measurement system  13601 . 
     The posture monitoring system  13601  may be configured to detect a deviation or potentially problematic posture condition by measuring an actual posture, which may be measured on a regular or continuous basis and used to generate results, which may be provided to the user through a graphical user interface of the electronic device  13610 .  FIG.  136 C  depicts an example posture that deviates from the ideal posture of  FIG.  136 B  and which may also represent a potentially problematic posture condition, which may be detected by the posture monitoring system  13601 . As shown in  FIG.  136 C , a location of each of the wireless tags  13600   a - 13600   f  may be determined with respect to a reference plane  13604 . If the positional offset of certain wireless tags  13600   a - 13600   f  falls outside of a range or exceeds a tolerance threshold, the system  13601  may determine that the user&#39;s current posture is potentially problematic or otherwise flag the posture event for the user. In some cases, the relative location of certain of the wireless tags  13600   a - 13600   f  is monitored with respect to a working envelope or other volume constraint and deviations that breach the reference working envelope or volume constraint are flagged. 
     The posture monitoring system  13601  may be configured to detect the user&#39;s posture using wireless locating signals received from one or more of the array of wireless tags  13600   a - 13600   f . In the example of  FIG.  136 C , the posture monitoring system  13601  may be used to detect a tilted posture in which the user&#39;s torso is slumped or leaned forward. The deviation may be determined using a comparison between a current relative position and a nominal or ideal position. In this example, the measured tilt plane  13606 , which may be determined using a comparison between the current position and a nominal position, may represent an angular deviation of the user&#39;s posture as determined based on the position of wireless tags  13600   a - 13600   d . The tilt plane  13606  is provided merely to demonstrate the amount of deviation, which may be represented using any number of different techniques, depending on the implementation. A visual representation of the measured deviation including for example, the tilt plane  13606 , may be provided to the user through a graphical user interface of the electronic device  13610  using another computer generated display. 
     Other example postures may be detected by the posture monitoring system  13601 . For example, the posture monitoring system  13601  may be used to detect one or more common static postures that may be associated with chronic back pain or other health issues. Example static postures include a hollow back posture in which the lumbar region of the user&#39;s back is displaced or distorted in a direction toward the front of the user&#39;s body. Other example static postures include a flat pelvis in which the curvature of the user&#39;s lumbar region is straightened or flattened as compared to an ideal or nominal posture. Other example postures include slumped postures, military postures, rounded shoulder postures and other similar postures that may be observed through the position or curvature of the user&#39;s back from the side of the user&#39;s body. These postures may generally be referred to as bend metrics. The posture-monitoring system  13601  may also be used to detect various postures, which may be characterized by tilt or twist metrics including, for example, high or displaced shoulders, high or displaced hips, head tilts, and spinal twists including scoliosis and other spinal defects. The posture-monitoring system  13601  may also be used to detect various non-static posture defects that may be evident in a user&#39;s gait, running stride, bending motion, sitting motion, or other non-static scenarios. 
     The user&#39;s posture may be monitored over time and/or measured on a regular interval. If the regular interval is sufficiently small (e.g., less than about 1 second), the posture measurement may be characterized as continuous or substantially continuous. The posture measurements may be stored in a data log and used to display results to a user on a graphical user interface of the electronic device  13610  when requested. In some cases, a series or set of body measurements are used to compute an animation of an avatar or other computer-generated model. The computed avatar or other computer-generated model may be displayed on a display of the electronic device  13610 . 
     In some cases, the body position or posture measurements are recorded in response to a determination that the user  13605  is in a static position. The static position may correspond to a standing static position, a sitting static position, a prone static position, or other static position. This determination may be made using the wireless locating signals (e.g., UWB beacon signals) a motion sensing system, accelerometers, magnetometers, or other sensors and sensing systems. If the user  13605  remains still for greater than a threshold amount of time (e.g., more than approximately 1 second), the system  13601  may determine that the user&#39;s position is at least momentarily static and a posture measurement or position measurement may be determined and stored in a log. In some cases, the one or more of the location sensors, particularly the leg sensors  13600   e  and  13600   f  are used to determine if the user  13605  is in static position, which may be used to trigger a posture measurement. In some cases, multiple posture measurements are taken and a time averaged or composite posture measurement is determined. 
     In some implementations, the user&#39;s position or posture is monitored by the posture-monitoring system  13601  for a minimum of 4 hours. In some cases, the user&#39;s posture is monitored by the posture-monitoring system  13601  for a minimum of 8 hours. In some cases, the user&#39;s posture is monitored by the posture-monitoring system  13601  for approximately 24 hours. In some cases, the user&#39;s posture is monitored by the posture-monitoring system  13601  for multiple days up to and including a week. In some cases, the user&#39;s posture is monitored by the posture-monitoring system  13601  for longer than a week. The user&#39;s posture may be monitored continuously or during periods in which it is predicted that the user is in a static posture. The static posture may correspond to a static condition, which may correspond to a standing, sitting, prone, sleeping, or other user position. 
     In some implementations, the posture-measurement system  13601  is configured to receive input from the user  13605  which may be used to indicate moments of pain or discomfort by the user  13605 . In some cases, events or time periods that are associated with user pain or discomfort are used to trigger a posture measurement or flag a posture measurement that has already been taken (on a continuous or regular interval basis). The posture measurement(s) taken during an interval associated with a pain or discomfort event may be displayed to a user or medical personnel and used to identify a potentially problematic posture condition. 
     The posture-measurement system  13601  may be used to determine a number of different posture conditions. As shown in  FIGS.  137 A and  137 B , a twist condition may be measured using wireless tags  13700   a  and  13700   b . In some cases, the twist condition is determined using a relative measurement between the wireless tags  13700   a  and  13700   b  and the other wireless tags (e.g.,  13600   c - 13600   f , the electronic device  13610 , or other device of  FIGS.  136 A- 136 C ). As mentioned previously, the wireless tags  13700   a  and  13700   b  may also include an orientation-detecting sensor like an accelerometer, magnetometer, or other sensor, which may be used to measure a relative angular position of the respective wireless tags  13700   a ,  13700   b  and used to determine shoulder twist measurement. 
     While the shoulder twist depicted in  FIGS.  137 A and  137 B  is provided as an illustrative example, other example measurements may also be determined using the posture-measurement system (e.g.,  13601  of  FIGS.  136 A- 136 C ). The measurements may include a variety of posture or spinal characteristics, which may be generally measured as rotational degrees of freedom: twist corresponding to an amount of rotation about a vertical or longitudinal axis roughly extending along a length of the user&#39;s spine; tilt corresponding to an amount of rotation about an axis that extends from the chest to the back of the user; and bend corresponding to an amount of rotation about an axis that extends from one side of the user to the other. By way of example, the posture-measurement system  13601  may be adapted to measure neck twist, upper back twist, lower back twist, hip twist, and other similar measurements. The posture-measurement system  13601  may be adapted to measure various tilt conditions including, for example, neck tilt, upper back tilt, lower back tilt, and other similar measurements. The posture-measurement system  13601  may also be adapted to measure various bend conditions including, for example, neck bend, upper back bend, lower back bend, and other similar measurements. 
     The number and location of the wireless tags may vary depending on the implementation.  FIG.  138 A  depicts one alternative arrangement of wireless tags  13800   a - 13800   e  that uses five wireless tags. As shown in  FIG.  138 A , the posture-measurement system  13801  includes a pair of wireless tags  13800   a  and  13800   b  that are positioned along a shoulder region of the user  13805 , a wireless tag  13800   d  that is positioned along a mid-back region of the user  13805 , and a wireless tag  13800   e  that is positioned along a lumbar region of the user  13805 . As shown in  FIG.  138 A , the posture-measurement system  13801  also includes a wireless tag  13800   c  that is positioned along the head of the user  13805 . The wireless tag  13800   c  may, in some cases, be integrated with a headset, eyeglass, or other head-mounted device or article worn by the user  13805 . 
     The configuration of wireless tags  13800   a - 13800   e  depicted in  FIG.  138 A  may be used to detect a variety of characteristics of the user&#39;s posture. For example, the wireless tags  13800   a - 13800   e  may be used to detect neck tilt, neck bend, upper back tilt, upper back bend, lower back tilt. and lower back bend. Other characteristics or measurements of the user&#39;s posture may also be measured or monitored using the wireless tags  13800   a - 13800   e  depicted in  FIG.  138 A  including shoulder dip, shoulder twist, and other body measurements. 
       FIG.  138 B  depicts one alternative arrangement of wireless tags  13850   a - 13850   d  that uses four wireless tags. As shown in  FIG.  138 B , the posture-measurement system  13851  includes a wireless tag  13850   b  that is positioned between the shoulders of the user  13855 , a wireless tag  13850   c  that is positioned along a mid-back region of the user  13855 , and a wireless tag  13850   d  that is positioned along a lumbar region of the user  13855 . As shown in  FIG.  138 B , the posture-measurement system  13851  also includes a wireless tag  13850   a  that is positioned along the head of the user  13855 . The wireless tag  13850   a  may, in some cases, be integrated with a headset, eyeglass, or other head-mounted device or article worn by the user  13855 . 
     The configuration of wireless tags  13850   a - 13850   d  depicted in  FIG.  138 B  may be used to detect a variety of characteristics of the user&#39;s posture. For example, the wireless tags  13850   a - 13850   d  may be used to detect upper back tilt, lower back tilt. and lower back bend. Other characteristics or measurements of the user&#39;s posture may also be measured or monitored using the wireless tags  13850   a - 13850   d  depicted in  FIG.  138 B  including shoulder dip, shoulder twist, and other body measurements. In some cases, the wireless tag  13850   a  that is positioned along the head of the user  13855  may be used to measure neck tilt, neck bend, upper back bend, and other body measurements. 
     As described herein, an array of wireless tags may be used to measure and monitor a user&#39;s posture. Similarly, an array of wireless tags may be positioned at various locations of a user&#39;s body and used to measure and monitor other user activity. Thus, the posture-monitoring systems described above may also be referred to as, more general, position-monitoring systems or simply monitoring systems. A position-monitoring system may be configured to track location data for one or more wireless tags over a period of time in order to identify an activity type. Example activity types include, for example, a weight lifting activity, a running activity, a biking activity, a sport activity (e.g., basketball, football, soccer), a yoga activity, a rowing activity, or other type of physical activity. The position-monitoring system may be configured to track location data for one or more wireless tags over a period of time in order to identify an athletic move including, for example, a bicep curl, a running step or stride, a walking step, a baseball throw, a football throw, a rowing stroke, or other type of athletic move. The position-monitoring system may be configured to count the number of athletic moves and, in some cases, estimate a calorie expenditure or activity level based, at least in part, on the number of athletic moves. 
     By way of further example, an array of wireless tags may be used to monitor exercise or sporting activity, which may be used to compute a health metric like calories used or power output. The wireless tags may also be used to monitor the kinematics of the user&#39;s activity like a running stride, swim stroke, baseball pitch, golf swing, or other similar kinematic motion, athletic move, or activity. In some implementations, an array of wireless tags may be used to count repetitions (reps) or other motions during an exercise or sporting activity. As mentioned above, the rep or motion count may be used to determine a more accurate estimate of calories burned or degree of exercise performed. The motion tracking information performed using the array of wireless tags may also be combined with other health-monitoring data like a heart rate or distance estimate in order to determine an estimate of a number of calories burned or a degree/amount of exercise performed. 
     The various wireless tags may be attached or coupled to the user by a variety of techniques. In some implementations, one or more of the wireless tags are incorporated into an article of clothing like a shirt or pants. For example, the wireless tags may be secured in one or more pockets or pouches of the clothing article that are configured to hold the respective wireless tag against the user&#39;s body in a particular location. This may require that some portion of the clothing be tightly or snugly fitted against the user&#39;s body to prevent or reduce an amount of independent movement of the wireless tag with respect to the portion of the user&#39;s body being monitored. In some cases, one or more of the wireless tags are attached to the user using an elastic band or wrap that extends around a body part of the user. For example, one or more of the wireless tags may be incorporated into a torso wrap that includes a stretchable or elastic material that extends around the torso of the user. In some implementations, one or more of the wireless tags are directly attached to the user by an adhesive or using an athletic tape. 
     In some implementations, one or more of the wireless tags are preprogrammed or otherwise configured to track a particular region of the user&#39;s body. For example, a wireless tag may be preprogrammed or otherwise configured to be positioned along a user&#39;s left shoulder region. Similarly, a wireless tag may be preprogrammed or otherwise configured to be positioned along a user&#39;s middle back, lumbar, leg, arm, head, or other region of the user&#39;s body. The preprogramming or configuration of the wireless tag may include a calibration or other set of coded values that may facilitate the use of the wireless tag in a particular body position. In one specific example, a wireless tag that is configured to be positioned along a user&#39;s shoulder may be adapted to measure a relative twist with respect to a complementary wireless tag that is configured to be positioned on the user&#39;s opposite shoulder. 
     The wireless tags described with respect to  FIGS.  136 A- 138 B  may include some or all of the hardware elements and the functionality described with respect to other wirelessly locatable tags described herein. An example of the various hardware elements that may be included in the wireless tag are described below with respect to  FIG.  144   . In some cases, the wireless tags may be adapted to provide real-time feedback to the user regarding the user&#39;s posture or detected body position. For example, one or more of the wireless tags may be adapted to provide a haptic output, audio output, visual output, or other output signaling the user&#39;s compliance or non-compliance with a target or goal posture or body position. As described in more detail below, the wireless tags may also be used to generate an animation or computer-generated model that corresponds to the user&#39;s detected body posture or position, which may be displayed on a separated display or device. 
       FIG.  139    depicts an example process  13900  of using a posture-measurement system, as described herein. The process  13900  of  FIG.  139    may be implemented using any one of the posture-measurement systems described above with respect to  FIGS.  136 A- 136 C,  137 A- 137 B , and  138 A- 138 B. The process  13900  may be implemented on an electronic device of the system, including, for example, a mobile phone, tablet computer system, watch, notebook computer system, or other device having a processor and computer memory. 
     In operation  13902 , a user&#39;s posture is detected. As described above with respect to  FIG.  136 A , a posture monitoring system may include an array of wireless tags that are used to measure the relative location of various regions of a user&#39;s body. The positional measurements may be performed using a wireless time-of-flight measurement implemented using a UWB or other wireless measurement system. An orientation of one or more of the wireless tags may also be determined using the wireless measurement system, an accelerometer, a magnetometer, and/or another type of sensor. Each of the wireless tags may transmit a wireless locating signal which may be used to determine the relative position of the respective tag with respect to another wireless tag and/or a separate electronic device like a mobile phone, smart watch, or other portable electronic device. In some implementations, the separate electronic device receives a wireless locating signal from a set of wireless tags, the wireless locating signal indicating or used to measure a relative distance between the respective wireless tag and the electronic device. In some cases, the wireless locating signal indicates or is used to measure a relative distance between two wireless tags, or a wireless tag and another device or object. 
     In operation  13904 , the system determines if the measured posture violates a condition or criteria. Similar to as described above with respect to  FIGS.  136 B and  136 C , the posture monitoring system may be configured to detect a deviation of a user&#39;s posture with respect to an ideal or nominal posture position. The posture monitoring system may measure or detect the deviation with respect to a set of positional offsets that correspond to the relative location of the various wireless tags with respect to a datum plane or datum origin. If a positional offset exceeds a threshold or other constraint, the position may be flagged as violating the condition or criteria. The posture monitoring system may also be adapted to measure or detect the deviation using a working envelope or volumetric constraint. If one or more of the wireless tags breaches the working envelope or volumetric constraint, the position may be flagged as violating the condition or criteria. 
     In an alternative embodiment, the system may determine a posture condition or activity condition. For example, the system may be used to determine a static posture that is not measured relative to an ideal or nominal posture. The static posture may be analyzed to determine one or more characteristics of the posture, which may be reported or presented to the user in operation  13906 . Similarly, the system may be used to monitor a series of body positions, which may correspond to an activity or athletic move. By way of example, the system may use a series of position measurements taken using the wireless tags at a series of time intervals to monitor shoulder, arm, and/or torso movement during a golf swing, a baseball swing, a tennis swing, or other similar athletic move. By way of other example, the system may use a series of measurements taken using the wireless tags over a period of time or time interval to monitor a user&#39;s hip and leg position(s) during a running stride or walking gait. The posture and/or activity that is monitored using the system may be displayed to the user in a graphical manner, as explained below with respect to operation  13906 . 
     In operation  13906 , the system signals the posture to the user. As discussed previously, an indicia of the deviation or posture event may be provided to the user. In one example, the results of the posture measurement are displayed on an electronic device through a graphical user interface or other similar technique. As discussed previously, a tilt plane or other similar reference may be displayed, which may indicate the type and degree or extent of the deviation. In some cases, an anatomical representation of the user&#39;s body is displayed and one or more of the regions of the user&#39;s body are identified as being deviated from an ideal or nominal posture. The graphical user interface may also display a description of the problem and corrective actions or other diagnostic information to the user. 
     In one example embodiment, an animation is generated based on location or posture information obtained using the wireless tags of the posture-monitoring system. The animation may include an avatar or other computer-generated representation of the user. The position and/or motion simulated by the avatar may correspond to a position or motion of the user that is being tracked with the wireless tags. The animation or computer-simulated avatar may be used to help diagnose or identify potential issues with a user&#39;s posture. The location information obtained from the wireless tags may also be used to generate other graphical feedback or information that is presented to the user. In one example, the location information is used to determine an amount of deviation from a nominal or ideal posture. The amount of deviation may correspond to an amount of time or number of deviations in which the user&#39;s posture exceeded a threshold with respect to the nominal or ideal posture. In some cases, the deviation or other measurement metric is displayed graphically on a histogram, bar graph, chart, or other graphical representation. 
     Similarly, a static posture and/or user activity may be displayed using one of a variety of graphical techniques. For example, an avatar or other computer-generated representation of the user&#39;s body may be displayed in a position that corresponds to the position and/or posture monitored using the wireless tags of the system. Similarly, an animation of an avatar or other representation of the user&#39;s body may be computed using a series of positions captured using the wireless tags over a period of time or multiple time intervals. In some cases, the animation and/or static representation of the user&#39;s activity or posture may be used to diagnose a condition, improve an athletic move, diagnose a run stride, diagnose a walking gait, or perform other further analysis. Additionally, a haptic output, audio output, and/or visual output may be provided by individual wireless tags when the user&#39;s posture or position is determined to be out of compliance and/or in compliance with a goal or target position or posture. For example, one or more of the wireless tags may produce a haptic output that is perceptible along a corresponding region of the user&#39;s body that is out of position or otherwise violates a criteria or working envelope of the goal or target position or posture, which may help the user to correct the position or posture in real time. The output provided by the wireless tags may be used as an alternative to a separate display and/or in concert with a separate display to provide feedback to the user. 
     As described above, wirelessly locatable tags may be used to help find and retrieve lost and/or misplaced items. For example, a user can use a smartphone or other computing device to request and receive location data of a wirelessly locatable tag via the device-location relay network. This is merely one example use case for wirelessly locatable tags, however, and because the spatial parameters (e.g., position, location, orientation) of tags can be determined with a high degree of accuracy, the tags described herein (or any device incorporating the systems and/or features of the tags) may enable myriad new or improved location-based functions and use cases. Several additional examples of applications for wirelessly locatable tags are described herein. These uses and applications may be performed by any of the tags described herein. 
     Using the localization features of the wirelessly locatable tags (or other devices that include tags or include the functionality of the tags), a user may be able to establish geographic and/or location-based rules for their devices. For example, a user can establish a rule that if the user&#39;s tag (which may be in the user&#39;s wallet) and phone are separated by a threshold distance, the user should be alerted. Another example rule may be that if a user&#39;s tag remains near the user&#39;s home while the user&#39;s phone is away from home (e.g., 100 feet away), the user should be alerted. Another type of geographic and/or location-based rule may help avoid false reports of lost tags. For example, a user may be able to establish locations or geographic areas in which the tag will not report itself as being “lost,” so that other devices (e.g., devices not associated with the tag&#39;s owner) do not report the location of the tag. 
     Geographic and/or location based rules may be executed by a device other than the tag itself. For example, a user&#39;s smartphone, laptop or desktop computer, or other device may monitor the locations of a user&#39;s keys and a user&#39;s wallet (each of which may be attached to a tag), and alert the user when the threshold distance between the keys and wallet is reached. A notification may include sending a text message, email, push notification, haptic notification (via the user&#39;s phone or watch), or any other suitable notification technique. Distances between any example devices (including between tags) may be monitored (by a smartphone or other device of a user), and the user may be notified if the distance between the devices exceeds a threshold distance (or if any other distance condition is satisfied). 
     Notably, the localization techniques facilitated by the device-location relay network, such as using UWB signals, allow the location of a tag or other device to be determined to a high degree of accuracy (e.g., less than about three feet, less than about 1 foot, less than about 3 inches, or with even greater accuracy). Accordingly, the device-location relay network may allow a user to establish geographic and/or location-based rules that are more granular than previous techniques. For example, a user may establish a rule that they wish to be notified if their car keys have been placed in a drawer instead of on a countertop. Other types of high-resolution location-based rules and measurements are also feasible as a result of the improved location-finding accuracy. 
     Geographic and/or location based rules may be executed by a device that is controlled by the user (and/or in the user&#39;s possession) to help ensure security of the user&#39;s information. For example, instead of a remote server system accessing the locations of a user&#39;s tags to evaluate geographic and/or location-based rule sets, a user&#39;s phone may receive or access location reports of the user&#39;s tags, and the phone may determine when certain rules are satisfied. In some cases, a user may have multiple trusted devices that can individually or collectively evaluate the user&#39;s geographic and/or location-based rules. For example, a user&#39;s laptop computer, phone, tablet, desktop computer, home automation system, or the like, may all be authorized to access the location reports of the user&#39;s tags (or determine a location of a tag at least in part from signals received directly from a tag) and determine when a rule condition is satisfied. 
     In these examples, as well as others described herein, a tag&#39;s spatial parameters may be determined in various ways. For example, in some cases, any device in the device-location relay network (even those not associated with the owner of a tag) may detect a signal from a tag, determine or estimate a location of the tag, and send a location report to a server of a cloud-based service. The owner of the tag may then access those location reports at any time. In other cases, a user&#39;s own device(s) may determine the position and/or location of the user&#39;s nearby tags in real-time. Thus, for example, if a user wishes to know the location of his nearby tags, he may cause his phone (or other device) to communicate directly with the nearby tags to determine their locations, or at least their positions relative to other devices. Direct communications with a tag (e.g., using UWB to determine the position of the tag) may provide faster, real-time location information than retrieving location reports, and may enable additional use cases and features that would be less practical if all location information were served to the user&#39;s devices from a remote, cloud-based system. For ease of reference, it will be understood that both of these techniques are considered to be provided by the device-location relay network, regardless of whether a cloud-based system is accessed, or if only the user&#39;s own devices are used to determine spatial parameters of tags via local communications (direct tag-to-phone communications, for example). 
     Due to its high accuracy, the device-location relay network may allow accurate distance measurements between tags. For example, if two objects have tags coupled to them, the device-location relay network may determine the location of each tag (e.g., using UWB location-finding techniques described herein) and determine the distance between the objects based on the absolute locations of the tags. Measuring a distance between two objects may be used for geofencing rules that rely on relative positions or distances between two objects, as described above. For example, as described above, a user may establish a rule that he wants to receive a notification if his wallet and keys are more than ten feet apart. The device-location relay network may monitor the distance between those objects and trigger notifications when the distance condition is satisfied. As another example, speakers of a home audio system may each have attached tags (or incorporate components of a tag), and the device-location relay network may measure the distance between tags, the position of tags relative to each other, and/or the orientation of the tags (and thus the speakers) to help the user position and/or align the speakers in their home environment. As yet another example, a user may place a tag on a vehicle bumper, and another on a garage wall. The device-location relay network may determine the distance between these tags and alert the user when they are within a threshold distance (e.g., to allow the user to park their car in a consistent and safe location and avoid a collision with the garage wall). As described above, the distance between tags may be determined based on tag-to-tag communications, and the orientations of tags may be determined using magnetometers, accelerometers, or the like. 
     Tags may also be used to help a user track their own path of travel. For example, a user may leave tags behind as they hike, walk, or move about an environment. The device-location relay network may allow the user to use the locations of the tags (which may be supplied via other devices in the device-location relay network) to retrace their path. For example, the user&#39;s phone may display a compass-like directional indicator indicating which way to travel to reach the next tag, or it may display a map showing the locations of the tags (and an optional path defined by the tag locations). Because phones and other devices can determine the direction to a tag locally (e.g., without accessing a remote server or host system), this pathfinding technique can be used even in remote locations where cellular or other network service is unavailable. 
     When permitted by a user, tags may also be used to track the locations of individuals for search-and-rescue or other emergency operations. For example, a skier, hiker, cyclist, mountaineer, or other individual may attach a tag to themselves so that rescuers can find the individual in the case of an emergency such as an avalanche, blizzard, accident, or the like. Even outside of recreational uses, tags may help rescuers or other emergency personnel locate individuals who are in trouble. For example, after an earthquake, hurricane, fire, medical event, or any other time it may be advantageous for an individual to be easily located by others, the individual may selectively permit the device-location relay network to access and report his or her location to other users. More particularly, a user who has a tag on or near their person may use their phone (or other device) to report themselves to the device-location relay network as “in need of assistance” or another such designation. This may allow the device-location relay network to report the location of the user&#39;s tag to medical personnel, firefighters, police, family, or other service providers so that the user can be more easily found and assisted. 
     In some cases, a user may select a particular triggering event that will cause their location to become public. For example, an individual may establish a rule that if their location does not change during a thirty minute interval, then they should be reported to the device-location relay network as “in need of assistance,” at which time the location reports of the user&#39;s tag (or other device) may be accessible to emergency personnel or predetermined contacts. Such rules may help ensure that a user who has become unable to manually initiate an assistance request (e.g., due to an injury during a recreational activity, a fall, a storm or fire, or the like) can still take advantage of the location-finding abilities of the device-location relay network, while also still maintaining control over their personal location information. 
     The device-location relay network may also be used to help map three-dimensional spaces using one or more tags or devices. For example, a user may carry a tag on their person as they go about their day, or move other devices or tags around their environment (e.g., placing their keys or phone on various surfaces or objects). The device-location relay network may securely monitor the location of the tags and, over time, construct a three-dimensional model of the user&#39;s home or work environment. More particularly, the tags&#39; locations may be analyzed by one or more of the user&#39;s devices to predict the locations of tables, furniture, walls, and other physical objects and obstacles in the user&#39;s environment. For example, if a map of a tag&#39;s location over time shows that the tag is often at rest in a location that is about three feet above the ground, and within an area of about three feet by six feet, the user&#39;s device(s) may infer that that location corresponds to a table. In this way, a user&#39;s devices may generate a three-dimensional map of an area based on location history of one or more tags. This information may then be used, for example, to help a user locate objects, avoid obstacles, or identify patterns of behavior and/or motion. If the user then loses her wallet and uses the device-location relay network to help find it, she may be provided with an automatically generated suggestion that it may be on the “kitchen table,” even if the user has never manually established or input a location of a table. 
     In some cases, users may manually establish the locations of physical objects in their environment by touching a tag to the object and associating that location with a particular object. For example, a user may initiate a location-learning mode (e.g., by applying an input to the tag or to another device) and then place a tag on a table. The device-location relay network may then determine the location of the tag and allow the user to associate that location with the object “table” (e.g., via an interface on the user&#39;s phone or computer). A user may perform a similar action with other objects as well, such as walls, desks, doors, beds, closets, pools, or any other suitable object. Where maps of a user&#39;s environment are generated, they may be securely stored and accessible only to the user. For example, they may be stored locally on one or more of the user&#39;s own devices, or they may be encrypted or otherwise secured and stored remotely (e.g., on a server associated with the cloud-based service). 
     Tags may also be used to help users locate and interact with stationary objects. For example, a tag may be placed at or near an emergency exit to a building so that, when needed, individuals can use their phone or other device to locate and navigate to the emergency exit (e.g., by showing a direction-indicating arrow on the screen of their phone or other device to guide them towards the exit). Similarly, tags may be placed at multiple locations along an exit route so that users&#39; phones can locate the tags and guide a user along the exit route. The tags may even communicate information to the devices such as identifiers of the physical structure or object that they are associated with. For example, when a phone or tablet communicates with a tag to determine a location of the tag, the tag may send information to the phone or tablet. The information may include, for example, a name of the associated object (e.g., fire exit, fire extinguisher, defibrillator, etc.), a physical location of the object (e.g., ground floor, front hallway, etc.), or the like. Such information may be stored by the tags, and may be provided to other devices as part of a location-finding process, or it may be broadcast periodically regardless of whether the information has been explicitly requested. 
       FIG.  140    illustrates an example environment with objects that are associated with wirelessly locatable tags, and an example device providing a user interface that directs a user to the location of the objects. For example,  FIG.  140    illustrates an example user device  14000 , such as a smartphone in use in a building that has an automatic electric defibrillator (AED)  14002  and a fire extinguisher  14004 . The AED  14002  and the fire extinguisher  14004  may each be associated with a respective tag. For example, a tag may be mounted on or near each object. The tags may be attached to a mounting base, such as the mounting base  6108 ,  FIG.  61 A , so that the tags can be powered indefinitely and without requiring batteries to be changed. 
     The device  14000  may determine the position of each object by communicating with each tag. For example, the tags may send signals using Bluetooth and/or UWB communication protocols, and the device  14000  may use techniques such as time of flight (ToF), angle of arrival (AoA), time difference of arrival (TDOA), received signal strength indication (RSSI), triangulation, synthetic aperture, and/or any other suitable technique, to determine positions of the tags relative to the device  14000 . Using the detected position of the tags (and optionally spatial parameters of the device  14000  from onboard sensors such as accelerometers, magnetometers, gyroscopes, GPS systems, or the like), the device  14000  may display a directional indicator that points towards the tags. As shown in  FIG.  140   , the device  14000  displays, on a display such as a touchscreen display, a first directional indicator  14008  (e.g., an arrow) that points towards the AED  14002 , and a second directional indicator  14010  (e.g., an arrow) that points towards the fire extinguisher. The device  14000  also displays a name (or other information) of each device, which may have been provided to the device  14000  from the tags themselves, as described above. 
     The objects and indicators shown in  FIG.  140    are merely examples, however, and the same or similar techniques may be used to direct users to other objects as well. For example, a museum may place tags at or near exhibits to help visitors find the exhibits, stores may place tags at or near product displays to help users find products or navigate through a store, or buildings may place tags at or near entrances or along hallways to help a user navigate the building. These tags may similarly provide information about the location or object with which they are associated. For example, a tag placed near the Mona Lisa may allow a user&#39;s phone to find a distance and direction to the famous portrait, and also provide information about the portrait directly to the user&#39;s phone. 
     Tags in buildings and other structures may also be employed to help individuals with vision impairment navigate the buildings or structures. For example, assistive devices may determine the distance to and/or location of various tags positioned in an area, and provide outputs to a user that can help them navigate the area. As one specific example, an assistive device on the person of a user may communicate with nearby tags on walls or other obstacles to determine a distance between the device and the nearby tags. The assistive device may provide an output to the user to indicate the distance and/or direction to the tags (or to a path that avoids the tags) to help the user avoid those areas. One example output from an assistive device may be a subtle vibration with a frequency that increases as the distance between the device and the tag decreases. 
     In cases where tags are mounted on obstacles or walls, the tags may store offset information that indicates where a device (e.g., an assistive device, smartphone) should direct the user. Thus, instead of a tag causing a device to direct a user towards an obstacle, the tag instead causes the device to direct the user to a location or along a path that avoids the obstacle. The offset information may be sent to the user&#39;s device, which may then determine where to direct the user based on the tag&#39;s detected location, the offset, and the device&#39;s location. 
     Tags may also be placed along paths, trails, ski runs, or other outdoor environments to help guide users. Such tags may also facilitate or trigger the display of objects in an augmented reality environment. For example, a user can raise his or her phone to a tag on a ski run to cause a name of the ski run to be presented on the user&#39;s phone display. 
     Tags may also be used for augmented reality (AR) applications. In particular, because the spatial parameters of a tag can be determined with a high degree of accuracy (e.g., within a foot of the actual location, or less), a device such as a phone, tablet, head-mounted display, or the like, may use onboard sensors (e.g., magnetometers, accelerometers, inertial positioning systems, GPS) to determine how the device is oriented relative to the tag. The device may take some action or display some information to the user as a result of detecting that the device is pointed at the tag. For example, if a tag is positioned next to a light switch, a user may direct her phone camera towards the tag, which may cause her phone&#39;s display to automatically show information about the light switch, such as what light it controls. The information may be integrated into the real-time image preview shown on the user&#39;s phone, thus providing an AR interface. As another example, a tag next to the Mona Lisa may cause a description of the famous painting to appear, in a device display, next to the Mona Lisa itself. As yet another example, a user may scan a phone&#39;s camera around a room or environment, and the locations and/or descriptions of detectable tags may be indicated on the image preview (e.g., with an item description bubble and arrow pointing to the tag). In this way, the user can easily visualize the location of various different tags in an environment. 
       FIGS.  141 A- 141 B  illustrate an example scenario in which a user is directed to a tag using an augmented reality application. In the illustrated example, a user is attempting to locate a tag  14102  using a device  14100  (e.g., a smartphone). The tag  14102  may be attached to a set of keys, a wallet, a smartwatch, a purse, or another object, though for simplicity only the tag  14102  is illustrated in the figures. 
     The device  14100  may display an AR interface  14104  on a display. The AR interface may include a live preview of the environment from a camera of the device  14100 . The device  14100  may determine the position and/or location of the tag  14102  using techniques described herein (e.g., using time of flight analysis on a UWB signal from the tag  14102 ). Based on the tag&#39;s position and the orientation of the device  14100  relative to the tag (e.g., the direction that the camera of the device  14100  is pointing relative to the position of the tag  14102 ), the device may determine how the device&#39;s orientation would need to be changed in order to bring the tag  14102  into the camera&#39;s field of view. The device may then display a directional indicator  14106 , such as an arrow, that indicates to the user where to point or reorient the device  14100  to locate the tag  14102 .  FIG.  141 A  shows the device  14100  oriented in a direction that does not show the tag  14102 . Accordingly, the AR interface  14104  shows a live preview from the device&#39;s camera, as well as the directional indicator  14106 .  FIG.  141 B  shows the device  14100  after the user has reoriented the device in accordance with the direction indicated by the directional indicator  14106 . The AR interface  14104  has been updated to show the live preview of the new portion of the environment, and shows the tag  14102 , as well as an updated directional indicator  14108  showing the detected position or location of the tag  14102 . In some cases, a different type of graphical object may indicate the location of the tag  14102 . For example, an object (e.g., a balloon, star, flashing light, or the like) may be shown hovering over or near the tag  14102 . The graphical object may be displayed even when the tag  14102  is obscured or occluded, such as if the tag  14102  is in a drawer, under a stack of papers, or otherwise not visible. 
     The directional indicators in the AR interface  14104  may be continuously updated based on the position of the tag  14102  relative to the device  14100  (and optionally the orientation of the device  14100 ). Thus, for example, as the user moves and/or reorients the device  14100  while viewing the AR interface  14104 , the directional indicators may be continuously updated to point the user towards one or more tags. The user may thus use the directional indicator as a compass-like guide that ultimately directs the user to the tag. 
     In some cases, multiple properties of a directional indicator change based on the distance to a tag. For example, the length of a displayed arrow may vary in accordance with the distance between the device  14100  and the tag  14102  (e.g., with a longer arrow indicating a greater distance), while the direction of the arrow indicates the position of the tag relative to the device  14100 . Other types of information may also be displayed on the AR interface  14104 , such as a numerical indicator of the distance to an object (e.g., in feet or meters), a proposed direction to move the device  14100  (e.g., up, down, left, right), or the like. 
     Devices other than tags, but which include the functions of a tag, may also be located and displayed to a user in an AR interface. For example, laptop computers, tablet computers, smartphones, WiFi routers, or the like, may include the same or similar components as the tag, and thus may be located by a device and incorporated into an AR interface. This may help a user find their own devices or devices with which they may want to interact. For example, a user can use a smartphone to view an AR interface that shows a live preview of the environment (through the camera). The AR interface may direct the user towards wirelessly locatable devices, and when such objects are within the live preview, show the device and a description of the device. In a specific example, the user can use the AR interface to scan or view a room to find a WiFi router so that he can approach the router to establish a connection. When the user points his or her phone camera towards the WiFi router, a graphical object may appear on the display indicating that the object is a WiFi router, and optionally provide information about the router such as an associated network name, password, wireless protocol, or the like. 
     Tags may also be used to facilitate augmented reality for gaming or other entertainment purposes. For example, tags may be used as game pieces. Because the devices can determine the locations of the tags with high accuracy, the devices can visually replace the tags in an augmented reality environment with computer-generated graphics. As one specific example, a game of chess may be played with each piece representing one of the chess pieces. Users may view the tags through a headset (or other device) and the headset may replace the images of the tags with animations of the chess characters, including animated battles between the characters, or the like. 
     As another example, tags may be attached to a user&#39;s body to allow a computer system to track the position of the tags and use position and changes in position (e.g., motion) of the tags to control an avatar that is displayed on a display (e.g., a television, head-mounted display), or the like.  FIG.  142    illustrates an example user  14200  with multiple tags  14202  attached to his or her body or clothes. A computer system  14205  may determine the position and/or location of the tags  14202  (including the relative locations of each tag to each other), and use the detected spatial parameters to control the appearance and/or motion of an avatar  14206  (or other graphical object) displayed on a display  14204 . The computer system  14205  may be a single device that is capable of determining the spatial parameters of the tags  14202  (using the techniques described above, such as ToF analysis of UWB signals). The computer system  14205  may be a desktop computer, gaming console, mobile phone, home automation system, or any other suitable device. In some cases, the computer system  14205  shown in  FIG.  142    represents multiple devices working in concert to determine the spatial parameters and/or motions of the tags  14202 . For example, multiple computers, gaming consoles, phones, tablets, or the like may cooperate to determine the spatial parameters of the tags  14202  and/or to generate or control a displayed avatar. 
     The application shown in  FIG.  142   , in which a user&#39;s body motions are tracked and used to control an avatar or other character on a display, may be used for various different applications. For example, an exercise or physical therapy program may display an example of a motion to be performed, and then monitor the actual motion of the user. The user&#39;s actual movements may be evaluated by the program to determine if they meet the displayed suggested movements, and optionally to provide additional guidance on how to perform the exercise. The user&#39;s motion may also be evaluated to count repetitions of an exercise, evaluate a user&#39;s flexibility, or the like. 
     A user&#39;s body motions may also be used to control an avatar in a game or augmented or virtual reality environment. For example, the user&#39;s body movements may be tracked and translated into movements of the in-game or in-environment avatar, which may in turn interact with other in-game or in-environment objects or characters. 
     The device-location relay network may also use the highly accurate distance- and/or position-finding functions for features that are not necessarily evident to a user. For example, a long-range wireless charging system may be able to improve its operation by having accurate position estimates of devices in its range. More particularly, a long-range wireless charging system may use highly directional, aimable electromagnetic signals to wirelessly charge devices such as phones, tablets, notebook computers, and the like. The charging system may use the device-location relay network (e.g., using a peer-to-peer communication scheme) to determine the position of a device to be charged, relative to the charging system. The charging system may then direct or aim its electromagnetic signals to that position to charge the device (e.g., using beamforming techniques). The charging system may also track a moving device with its electromagnetic signals by continuously monitoring or updating the position of the device to be charged. Similar techniques may be used for any suitable type of highly directional wireless signals (e.g., optical communications, wireless communications signals, etc.). 
     The accuracy of the position measurements provided by the tags and the device-location relay network may also have unique applications in sports and other recreational activities. For example, tags may be placed on a user&#39;s body to track and analyze motions to improve performance. More particularly, tags may be placed on a user&#39;s arms, back, head, legs, torso, or any other suitable location (including on sporting equipment such as golf clubs, basketballs, baseball bats, and the like). Devices may then be used to track the position of each of the tags in three-dimensional space and develop biometric models and/or animations of the user&#39;s motions. In this way, golf swings, baseball swings, basketball shots, volleyball strikes, or any other type of sports or recreation motion may be recorded for analysis and training purposes. Multiple tags may be attached to a user to track and/or record complex multi-dimensional body movements, posture, form, etc. 
     In some cases, tags may have feedback systems that can indicate to a user if their motion or form deviates from a target. For example, if a user bends his knees too far during a basketball shot, haptic output systems on leg-based tags may provide a haptic notification to the user indicating the deviation or error. Tags (or the systems typically provided in tags) may also be integrated into sports equipment such as golf balls (e.g., to monitor trajectory and speed, to assist in lost-ball retrieval), golf clubs, basketballs, baseballs, baseball bats, and so forth. In some cases, tags may include accelerometers, gyroscopes, or other components, which may improve or expand the biometric data captured by the tags in sporting and recreation contexts. Even outside the context of sports or recreation, tags may be used to measure users&#39; motions for other purposes such as object tracking. For example, if a tag on a wallet is found to move along a path that is indicative of removal from a pocket, the location of that event may be recorded by the users&#39; devices so that the user can be reminded at a later time where the wallet was removed from a pocket. 
     Tags may also be used to help track the locations of and the users of shared resources. For example, communities or companies may provide resources such as cars, bicycles, scooters, or other equipment (e.g., tools, computers, library books, etc.) that may be temporarily used by multiple individuals. Such resources may have tags attached to them, and the tags may facilitate the recording of who is using or has used the resource, and where the resource is located. As a specific example, a user may approach a shareable vehicle and touch his or her phone to a wirelessly locatable tag on the vehicle. The act of touching the phone to the tag may cause the NFC communications system of the tag and phone to communicate (including the tag providing a unique identifier of itself and/or the vehicle to the phone), and may initiate a checkout operation in which the user gains access to the vehicle. The location of the vehicle may be updated by the user&#39;s phone (as well as the devices of other individuals in the device-location relay network). Because the devices in the device-location relay network are able to periodically update the location of the tag, it may be possible for users to determine the locations of the shared resources. Thus, if a shared scooter is driven to another location by a first user, another user may be able to find the location of the scooter (as updated by the first user or by other devices in the device-location relay network) by accessing the location reports of the scooter. In cases where it is desirable for multiple individuals to access location reports of a tag (such as in the case of shared resources), each authorized individual may have a copy of a private key for a particular tag, or another authorization scheme may be used so that each authorized individual can access the location reports in a secure manner. 
     The foregoing examples of use cases for the device-location relay network are merely some example use cases, and are not limiting. Indeed, any tags may be associated with or attached to any suitable object to facilitate distance, position, location, and/or motion tracking, initiate augmented reality objects, provide navigational cues, or the like. Additional objects that may be associated with tags may include, for example, jewelry, bicycles, motorcycles, cars, scooters, vehicles, clothes, glasses, retail inventory (e.g., for theft prevention and recovery), industrial applications (e.g., for tracking products along an assembly line, for tracking materials through a supply chain, for measuring distances or tracking construction equipment or materials, etc.), musical instruments, flashlights, first aid kits, automatic electronic defibrillators, mail, packages, shoes, helmets, medicine containers, pets, animals (e.g., for studying migration, preventing poaching, etc.), and so forth. 
     In order to facilitate the detection of tags, devices that are capable of communicating with tags or otherwise receiving location reports of tags may include a tag-finding application or interface that shows a list of nearby tags. The list of nearby tags may include any and all tags that are associated with the user (e.g., the user&#39;s own tags) as well as any publicly accessible tags and tags that the user is authorized to see. Thus, when the user opens the tag-finding application, he or she may see a list of tags, each with an identifier of an object or location that the tag is associated with (e.g., “wallet,” “car keys,” “Mona Lisa,” etc.). The user may then select a desired tag to get more information about the tag, such as the location of the tag, directions to the tag, a status of the tag, or the like. Users may also download or otherwise access groups of related tags. For example, a user may download or access a list of publicly accessible tags in the Guggenheim Museum, all of which may appear in the tag-finding application so that a user can view the locations and information associated with the tags. 
     In some cases, the location of the tags associated with or accessible by a user may be shown in a map view, allowing the user to visualize the location of the tags in a geographic environment. Or they may be shown in a “radar view,” where the relative positions of the tags are shown distributed about a central point that represents the user, without displaying a geographic map. Locations may also be reported by requesting location information about a tag from a digital assistant. For example, a user may ask a voice-based digital assistant “where are my keys,” which may cause the digital assistant to respond with a location of the keys (e.g., “in the kitchen” or “I&#39;ll show you on your phone”). 
     The tag-finding application may display tags that the user&#39;s device can communicate with directly (e.g., tags that are nearby the user when the application is open), and tags that are remote from the device. In the latter cases, the location information to the tag may not be generated via direct peer-to-peer communication between the user&#39;s device and the tag, but rather may be provided from location reports that have been provided to a cloud-based system. In this way, the tag-finding application can allow a user to locate tags that are remote from the user&#39;s device. The tag-finding application may also visually or otherwise differentiate between tags that are local (e.g., in direct peer-to-peer communication with the device) and those that are remote (e.g., those that are not in direct peer-to-peer communication with the device but are associated with last-known locations and/or location reports from a cloud-based system). 
     The tag-finding application may also help users locate other individuals. For example, individuals may choose to allow the location of their own tags and/or devices to be viewed by others. Thus, a family attending a theme park may all choose to allow their locations to be viewed by the other members of their family. The device-location relay network allows a family member&#39;s device to access the locations of the other family members, using either direct peer-to-peer communications with the other family members&#39; tags or devices if they are within range, or via remotely provided location reports (e.g., received from a cloud-based service). 
       FIG.  143    depicts an example schematic diagram of an electronic device  14300 . The electronic device  14300  may represent an electronic device that determines a location of a wirelessly locatable tag, or determines the location of any other electronic device that includes the components of or provides the functionality of a wirelessly locatable tag (e.g., a receiving device  206 ,  FIGS.  2 D- 2 F ). The electronic device  14300  as described represents a mobile phone (e.g., a smartphone), but it may also represent a laptop computer, tablet computer, desktop computer, personal digital assistant, watch (e.g., a smartwatch) or other wearable device, a wireless router or other network infrastructure device, a television, or any other suitable device. 
     The device  14300  includes one or more processing units  14301  that are configured to access a memory  14302  having instructions stored thereon. The instructions or computer programs may be configured to perform one or more of the operations or functions described with respect to the electronic devices described herein. For example, the instructions may be configured to control or coordinate the operation of one or more displays  14308 , one or more touch sensors  14303 , one or more force sensors  14305 , one or more communication channels  14304 , one or more audio input systems  14309 , one or more audio output systems  14310 , one or more positioning systems  14311 , one or more sensors  14312 , and/or one or more haptic feedback devices  14306 . 
     The processing units  14301  of  FIG.  143    may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processing units  14301  may include one or more of: a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or combinations of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitably configured computing element or elements. 
     The memory  14302  can store electronic data that can be used by the device  14300 . For example, a memory can store electrical data or content such as, for example, audio and video files, images, documents and applications, device settings and user preferences, programs, instructions, timing and control signals or data for the various modules, data structures or databases, and so on. The memory  14302  can be configured as any type of memory. By way of example only, the memory can be implemented as random access memory, read-only memory, Flash memory, removable memory, or other types of storage elements, or combinations of such devices. 
     The touch sensors  14303  may detect various types of touch-based inputs and generate signals or data that are able to be accessed using processor instructions. The touch sensors  14303  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, the touch sensors  14303  may be capacitive touch sensors, resistive touch sensors, acoustic wave sensors, or the like. The touch sensors  14303  may include any suitable components for detecting touch-based inputs and generating signals or data that are able to be accessed using processor instructions, including electrodes (e.g., electrode layers), physical components (e.g., substrates, spacing layers, structural supports, compressible elements, etc.) processors, circuitry, firmware, and the like. The touch sensors  14303  may be integrated with or otherwise configured to detect touch inputs applied to any portion of the device  14300 . For example, the touch sensors  14303  may be configured to detect touch inputs applied to any portion of the device  14300  that includes a display (and may be integrated with a display). The touch sensors  14303  may operate in conjunction with the force sensors  14305  to generate signals or data in response to touch inputs. A touch sensor or force sensor that is positioned over a display surface or otherwise integrated with a display may be referred to herein as a touch-sensitive display, force-sensitive display, or touchscreen. 
     The force sensors  14305  may detect various types of force-based inputs and generate signals or data that are able to be accessed using processor instructions. The force sensors  14305  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, the force sensors  14305  may be strain-based sensors, piezoelectric-based sensors, piezoresistive-based sensors, capacitive sensors, resistive sensors, or the like. The force sensors  14305  may include any suitable components for detecting force-based inputs and generating signals or data that are able to be accessed using processor instructions, including electrodes (e.g., electrode layers), physical components (e.g., substrates, spacing layers, structural supports, compressible elements, etc.) processors, circuitry, firmware, and the like. The force sensors  14305  may be used in conjunction with various input mechanisms to detect various types of inputs. For example, the force sensors  14305  may be used to detect presses or other force inputs that satisfy a force threshold (which may represent a more forceful input than is typical for a standard “touch” input). Like the touch sensors  14303 , the force sensors  14305  may be integrated with or otherwise configured to detect force inputs applied to any portion of the device  14300 . For example, the force sensors  14305  may be configured to detect force inputs applied to any portion of the device  14300  that includes a display (and may be integrated with a display). The force sensors  14305  may operate in conjunction with the touch sensors  14303  to generate signals or data in response to touch- and/or force-based inputs. 
     The device  14300  may also include one or more haptic devices  14306 . The haptic device  14306  may include one or more of a variety of haptic technologies such as, but not necessarily limited to, rotational haptic devices, linear actuators, piezoelectric devices, vibration elements, and so on. In general, the haptic device  14306  may be configured to provide punctuated and distinct feedback to a user of the device. More particularly, the haptic device  14306  may be adapted to produce a knock or tap sensation and/or a vibration sensation. Such haptic outputs may be provided in response to detection of touch and/or force inputs, and may be imparted to a user through the exterior surface of the device  14300  (e.g., via a glass or other surface that acts as a touch- and/or force-sensitive display or surface). Haptic outputs may also be provided in response to a detection that a condition of a wirelessly locatable tag has been met. For example, if a rule relating to the location of a tag is satisfied (e.g., if a tag is detected outside of a specified area or greater than a specified distance from a user or another device), the device  14300  may produce a haptic output using the haptic devices  14306 . 
     The one or more communication channels  14304  may include one or more wireless interface(s) that are adapted to provide communication between the processing unit(s)  14301  and an external device. The one or more communication channels  14304  may include antennas, communications circuitry, firmware, software, or any other components or systems that facilitate wireless communications with other devices (e.g., with wirelessly locatable tags or devices that include such functionality). In general, the one or more communication channels  14304  may be configured to transmit and receive data and/or signals that may be interpreted by instructions executed on the processing units  14301 . In some cases, the external device is part of an external communication network that is configured to exchange data with wireless devices. Generally, the wireless interface may communicate via, without limitation, radio frequency, optical, acoustic, and/or magnetic signals and may be configured to operate over a wireless interface or protocol. Example wireless interfaces include radio frequency cellular interfaces, fiber optic interfaces, acoustic interfaces, Bluetooth interfaces, infrared interfaces, USB interfaces, Wi-Fi interfaces, TCP/IP interfaces, network communications interfaces, or any conventional communication interfaces. The one or more communications channels  14304  may also include ultra-wideband interfaces, which may include any appropriate communications circuitry, instructions, and number and position of suitable UWB antennas to facilitate localization of a wirelessly locatable tag (or other device with similar functionality), as described herein. 
     As shown in  FIG.  143   , the device  14300  may include a battery  14307  that is used to store and provide power to the other components of the device  14300 . The battery  14307  may be a rechargeable power supply that is configured to provide power to the device  14300 . 
     The device  14300  may also include one or more displays  14308  configured to display graphical outputs. The displays  14308  may use any suitable display technology, including liquid crystal displays (LCD), organic light emitting diodes (OLED), active-matrix organic light-emitting diode displays (AMOLED), or the like. The displays  14308  may display information relating to the position or location of a wirelessly locatable tag, such as a graphical indicator that points to or otherwise directs a user to the location of a wirelessly locatable tag. 
     The device  14300  may also provide audio input functionality via one or more audio input systems  14309 . The audio input systems  14309  may include microphones, transducers, or other devices that capture sound for voice calls, video calls, audio recordings, video recordings, voice commands, and the like. 
     The device  14300  may also provide audio output functionality via one or more audio output systems (e.g., speakers)  14310 . The audio output systems  14310  may produce sound from voice calls, video calls, streaming or local audio content, streaming or local video content, or the like. The audio output systems  14310  may also provide audible outputs in response to a detection that a condition of a wirelessly locatable tag has been met. 
     The device  14300  may also include a positioning system  14311 . The positioning system  14311  may be configured to determine the location of the device  14300 . For example, the positioning system  14311  may include magnetometers, gyroscopes, accelerometers, optical sensors, cameras, global positioning system (GPS) receivers, inertial positioning systems, or the like. The positioning system  14311  may be used to determine spatial parameters of the device  14300 , such as the location of the device  14300  (e.g., geographical coordinates of the device), measurements or estimates of physical movement of the device  14300 , an orientation of the device  14300 , or the like. The positioning system  14311  may also be used to determine spatial parameters of another device, such as a wirelessly locatable tag. The positioning system  14311  may communicate with or otherwise interact with other components of the device  14300  to perform functions relating to localization of a wirelessly locatable tag, including but not limited to the processing units  14301 , memory  14302 , communications channels  14304 , and the like. For example, the positioning system  14311  may perform at least some of the localization processes described with respect to  FIGS.  2 D- 2 F . 
     The device  14300  may also include one or more additional sensors  14312  to receive inputs (e.g., from a user or another computer, device, system, network, etc.) or to detect any suitable property or parameter of the device, the environment surrounding the device, people or things interacting with the device (or nearby the device), or the like. For example, a device may include temperature sensors, biometric sensors (e.g., fingerprint sensors, photoplethysmographs, blood-oxygen sensors, blood sugar sensors, or the like), eye-tracking sensors, retinal scanners, humidity sensors, buttons, switches, lid-closure sensors, or the like. 
     To the extent that multiple functionalities, operations, and structures described with reference to  FIG.  143    are disclosed as being part of, incorporated into, or performed by the device  14300 , it should be understood that various embodiments may omit any or all such described functionalities, operations, and structures. Thus, different embodiments of the device  14300  may have some, none, or all of the various capabilities, apparatuses, physical features, modes, and operating parameters discussed herein. Further, the systems included in the device  14300  are not exclusive, and the device  14300  may include alternative or additional systems, components, modules, programs, instructions, or the like, that may be necessary or useful to perform the functions described herein. 
       FIG.  144    depicts an example schematic diagram of a wirelessly locatable tag  14400 . The wirelessly locatable tag  14400  may represent any of the wirelessly locatable tags, wireless tags, or wireless modules described herein, and may interact with an electronic device (such as the electronic device  14300 ) to facilitate localization of the wirelessly locatable tag  14400 . The wirelessly locatable tag  14400  as described represents a small, puck-shaped device. As noted above, however, other devices may include the components, systems, and/or modules of the wirelessly locatable tag  14400 , and may provide the same or similar functionality. Accordingly, the components, systems, and/or modules (and associated programs, operations, and/or instructions) described as being included in the wirelessly locatable tag  14400  may also be included in other devices, such as mobile phones (e.g., smartphones), laptop computers, tablet computers, desktop computers, personal digital assistants, watches (e.g., smartwatches) or other wearable devices, wireless routers or other network infrastructure devices, televisions, or any other suitable devices. 
     The tag  14400  includes one or more processing units  14401  that are configured to access a memory  14402  having instructions stored thereon. The instructions or computer programs may be configured to perform one or more of the operations or functions described with respect to the tags described herein. For example, the instructions may be configured to control or coordinate the operation of one or more communication channels  14404 , one or more audio input systems  14409 , one or more input devices  14303 , one or more audio output systems  14410 , one or more positioning systems  14411 , one or more sensors  14412 , one or more haptic feedback devices  14406 , and/or one or more optional displays  14408 . 
     The processing units  14401  of  FIG.  144    may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, the processing units  14401  may include one or more of: a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or combinations of such devices. As described herein, the term “processor” is meant to encompass a single processor or processing unit, multiple processors, multiple processing units, or other suitably configured computing element or elements. 
     The memory  14402  can store electronic data that can be used by the tag  14400 . For example, a memory can store electrical data or content such as, for example, device settings and user preferences, timing and control signals or data for the various modules, data structures or databases, programs, instructions, audio and video files, images, documents and applications, and so on. The memory  14402  can be configured as any type of memory. By way of example only, the memory can be implemented as random access memory, read-only memory, Flash memory, removable memory, or other types of storage elements, or combinations of such devices. 
     The input devices  14403  may detect various types of inputs and generate signals or data that are able to be accessed using processor instructions. The input devices  14403  may use any suitable components and may rely on any suitable phenomena to detect physical inputs. For example, an input device  14403  may be an audio system (such as the audio system  404 ) that detects inputs by detecting an electrical signal (e.g., voltage, current) in a coil as a result of the coil being moved in a magnetic field. Other types of input devices  14403  may include dome switches, capacitive sensors, resistive sensors, acoustic wave sensors, strain-based sensors, piezoelectric-based sensors, piezoresistive-based sensors, or the like. Input devices  14403  may be integrated with the housing of a tag such that a deflection or deformation of the housing, as a result of a user applying an input force to the exterior housing surface, actuates the input device or otherwise produces a detectable event that causes the tag to perform an action (e.g., changing a mode of operation, changing a beacon frequency, etc.). 
     The input devices  14403  may include touch sensors, which may in turn include any suitable components for detecting touch-based inputs and generating signals or data that are able to be accessed using processor instructions, including electrodes (e.g., electrode layers and/or an array of capacitive electrodes), physical components (e.g., substrates, spacing layers, structural supports, compressible elements, etc.) processors, circuitry, firmware, and the like. The touch sensors may be integrated with or otherwise configured to detect touch inputs applied to any portion of the tag  14400 . For example, the touch sensors may be configured to detect touch inputs applied to any portion of the tag  14400  that includes an optional display. Example touch inputs include momentary touches, taps, swipes, and other gesture and non-gesture input. The touch sensors may operate in conjunction with force sensors to generate signals or data in response to touch inputs that may correspond to a location of a touch or type of gesture provided to the input device  14403 . A touch sensor or force sensor that is positioned over a display surface or otherwise integrated with a display may be referred to herein as a touch-sensitive display, force-sensitive display, or touchscreen. 
     The input device  14403  may also include force sensors, which may in turn detect various types of force-based inputs and generate signals or data that are able to be accessed using processor instructions. The force sensors may use any suitable components and may rely on any suitable phenomena to detect force-based inputs. For example, the force sensors may be strain-based sensors, piezoelectric-based sensors, piezoresistive-based sensors, capacitive sensors, resistive sensors, or the like. The force sensors may include any suitable components for detecting force-based inputs and generating signals or data that correspond to a degree or magnitude of the force-based input and that are able to be accessed using processor instructions, including electrodes (e.g., electrode layers), physical components (e.g., substrates, spacing layers, structural supports, compressible elements, etc.) processors, circuitry, firmware, and the like. The force sensors may be used in conjunction with various input mechanisms to detect various types of inputs. For example, the force sensors may be used to detect a finger press, object press, or other force inputs that result in a force sensor output that satisfies a force threshold (which may represent a more forceful input than is typical for a standard “touch” input). Like the touch sensors, the force sensors may be integrated with or otherwise configured to detect force inputs applied to any suitable portion of the tag  14400 . For example, the force sensors may be configured to detect force inputs applied to any portion of the tag  14400  that includes an optional display (and may be integrated with a display). The force sensors may operate in conjunction with the touch sensors to generate signals or data in response to touch- and/or force-based inputs. 
     The tag  14400  may also provide audio output functionality via one or more audio output systems  14410 . The audio output systems  14410  may include an audio system that uses a housing member as a diaphragm to produce sound, as described above. The audio output systems  14410  may also provide audible outputs in response to a detection that a condition of a wirelessly locatable tag has been met, or a signal or instruction from another device (e.g., the device  14300 ), or the like. The audible output may be used to indicate a status of the tag (e.g., to indicate when the tag changes modes), to help a user locate a tag (e.g., by listening for a beep or tone), or the like. 
     The tag  14400  may also include one or more haptic devices  14406 . The haptic device  14406  may include one or more of a variety of haptic technologies such as, but not necessarily limited to, rotational haptic devices, linear actuators, piezoelectric devices, vibration elements, and so on. In general, the haptic device  14406  may be configured to provide punctuated and distinct feedback to a user of the device. More particularly, the haptic device  14406  may be adapted to produce a knock or tap sensation and/or a vibration sensation. Such haptic outputs may be provided in response to any suitable condition, such as a receipt of a wireless signal instructing the tag to produce an output (e.g., to help a user locate the tag). Haptic outputs form a haptic device  14406  may be imparted to a user through the exterior surface of the tag  14400  (e.g., via a housing member that defines an upper or top surface of the tag and also acts as a speaker diaphragm). Haptic outputs may also be provided in response to a detection that a condition of a wirelessly locatable tag has been satisfied. For example, if a rule relating to the location of a tag is satisfied (e.g., if a tag is detected outside of a specified area or greater than a specified distance from a user or another device), the tag  14400  may produce a haptic output using the haptic devices  14406 . As noted above, the haptic device  14406  may be part of an audio system that uses a housing member as a speaker diaphragm. In other cases, a dedicated haptic device, such as a linear resonant actuator, piezoelectric actuator, or the like, is provided. 
     The one or more communication channels  14404  may include one or more wireless interface(s) that are adapted to provide communication between the processing unit(s)  14401  and an external device (e.g., the electronic device  14300 ). The one or more communication channels  14404  may include antennas (e.g., the antennas described with respect to  FIGS.  8 A- 8 E ), communications circuitry, firmware, software, or any other components or systems that facilitate wireless communications with other devices (e.g., with devices that facilitate localization of the tag  14400 , such as the device  14300 ). In general, the one or more communication channels  14404  may be configured to transmit and receive data and/or signals that may be interpreted by instructions executed on the processing units  14401 . In some cases, the external device is part of an external communication network that is configured to exchange data with wireless devices. Generally, the wireless interface may communicate via, without limitation, radio frequency, optical, acoustic, and/or magnetic signals and may be configured to operate over a wireless interface or protocol. Example wireless interfaces include radio frequency cellular interfaces, fiber optic interfaces, acoustic interfaces, Bluetooth interfaces, infrared interfaces, USB interfaces, Wi-Fi interfaces, TCP/IP interfaces, network communications interfaces, or any conventional communication interfaces. The one or more communications channels  14404  may also include ultra-wideband interfaces, which may include any appropriate communications circuitry, instructions, and number and position of suitable UWB antennas to facilitate localization of the tag (or other tags or devices with similar functionality), as described herein. For example, the communications channels  14404  may perform at least some of the localization processes described with respect to  FIGS.  2 D- 2 F  (or otherwise be used as part of the localization processes or operations). For example, UWB antennas may be operable to send wireless beacon signals to other devices to facilitate localization of the tag  14400  or of other devices. 
     As shown in  FIG.  144   , the tag  14400  may include a battery  14407  that is used to store and provide power to the other components of the tag  14400 . The battery  14407  may represent the battery  514 , or any other battery described above. The battery  14407  may be a button cell battery, or any other suitable type of battery. The battery  14407  may be non-rechargeable, or it may be a rechargeable battery or other power supply that is configured to provide power to the tag  14400 . 
     The tag  14400  may also include a positioning system  14411 . The positioning system  14411  may be configured to determine the location of the tag  14400 . The positioning system  14411  may perform, manage, control, or otherwise facilitate localization operations such as those described with respect to  FIGS.  2 D- 2 F . The positioning system  14411  may optionally include other devices or systems, such as magnetometers, gyroscopes, accelerometers, optical sensors, cameras, global positioning system (GPS) receivers, inertial positioning systems, or the like. Such devices or systems may be used to determine spatial parameters of the tag  14400 , such as the location of the tag  14400  (e.g., geographical coordinates of the device), measurements or estimates of physical movement of the tag  14400 , an orientation of the tag  14400 , or the like. The positioning system  14411  may also be used to determine spatial parameters of another device, such as another wirelessly locatable tag, a smartphone, or any other suitably configured device. The positioning system may communicate with or otherwise interact with other components of the tag  14400 , including but not limited to the processing units  14401 , memory  14402 , and communications channels  14404 , to perform such functions or operations. 
     The tag  14400  may also include one or more additional sensors  14412  to receive inputs (e.g., from a user or another computer, device, system, network, etc.) or to detect any suitable property or parameter of the device, the environment surrounding the device, people or things interacting with the device (or nearby the device), or the like. For example, a device may include temperature sensors, barometric sensors, biometric sensors (e.g., fingerprint sensors, photoplethysmographs, blood-oxygen sensors, blood sugar sensors, or the like), eye-tracking sensors, retinal scanners, humidity sensors, electric field sensors, magnetic field sensors, buttons, switches, lid-closure sensors, or the like. 
     The tag  14400  may optionally include one or more displays  14408  configured to display graphical outputs. (Though, as noted above, in some cases tags  14400  may be devoid of displays or other visual output devices.) The optional displays  14408  may use any suitable display technology, including liquid crystal displays (LCD), organic light emitting diodes (OLED), active-matrix organic light-emitting diode displays (AMOLED), segmented LED display, or the like. The optional displays  14408  may display information relating to the operations, modes, functions, settings, or statuses of a wirelessly locatable tag. For example, a display may display “Lost” if the tag is in a “lost” mode or state, or “Not Lost” if it is in a “not lost” mode or state. In some cases, an optional display  14400  may include indicator lights (e.g., light sources that provide a single point or pixel of light). The indicator lights may be LEDs or any other suitable light sources, and may be positioned on a tag in a location that is visible to a user, such as on (or visible along) a top exterior surface, a bottom exterior surface, a peripheral exterior surface, or any other surface. In some cases, the LED or other light source may be positioned within the housing of the tag and proximate an optically transmissive portion of the housing (e.g., a glass, crystal, or plastic housing member or window), such that the light from the LED or other light source is protected in the housing and also visible from outside the tag. The indicator lights may indicate a status of the device, such as a power state, battery charge level, operating mode, lost/not lost status, or the like. In some cases, the indicator lights may be activated in response to the tag being reported lost. For example, the indicator lights may flash (or remain steadily illuminated) to alert nearby people to the presence of the tag and its status as being lost. The indicator lights may be used for other purposes as well. 
     The tag  14400  may also optionally provide audio input functionality via one or more audio input systems  14409 . The audio input systems  14409  may include microphones, transducers, or other devices that capture sound for recording sound content (e.g., vocal recordings to be played back by the tag), receiving voice commands for controlling operation of the tag, or the like. 
     To the extent that multiple functionalities, operations, and structures described with reference to  FIG.  144    are disclosed as being part of, incorporated into, or performed by the tag  14400 , it should be understood that various embodiments may omit any or all such described functionalities, operations, and structures. Thus, different embodiments of the tag  14400  may have some, none, or all of the various capabilities, apparatuses, physical features, modes, and operating parameters discussed herein. Further, the systems included in the tag  14400  are not exclusive, and the tag  14400  may include alternative or additional systems, components, modules, programs, instructions, or the like, that may be necessary or useful to perform the functions described herein. 
     As described above, one aspect of the present technology is the gathering and use of data available from specific and legitimate sources to provide the ability to track and find objects. The present disclosure contemplates that, in some instances, this gathered data may include personal information data that uniquely identifies or can be used to identify a specific person. Such personal information data can include demographic data, location-based data (e.g., locations, movements, positions, paths, etc., of a person and/or the person&#39;s belongings, devices, home environments, etc.), online identifiers, telephone numbers, email addresses, home addresses, data or records relating to a user&#39;s health or level of fitness (e.g., vital signs measurements, medication information, exercise information), date of birth, or any other personal information. 
     The present disclosure recognizes that the use of such personal information data, in the present technology, can be used to the benefit of users. For example, locations of a user&#39;s tags may be recorded to allow users to find their lost possessions. Further, other uses for personal information data that benefit the user are also contemplated by the present disclosure. For instance, health and fitness data may be used, in accordance with the user&#39;s preferences, to provide insights into their general wellness, or may be used as positive feedback to individuals using technology to pursue wellness goals. 
     The present disclosure contemplates that those entities responsible for the collection, analysis, disclosure, transfer, storage, or other use of such personal information data will comply with well-established privacy policies and/or privacy practices. In particular, such entities would be expected to implement and consistently apply privacy practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. Such information regarding the use of personal data should be prominent and easily accessible by users, and should be updated as the collection and/or use of data changes. Personal information from users should be collected for legitimate uses only. Further, such collection/sharing should occur only after receiving the consent of the users or other legitimate basis specified in applicable law. Additionally, such entities should consider taking any needed steps for safeguarding and securing access to such personal information data and ensuring that others with access to the personal information data adhere to their privacy policies and procedures. Further, such entities can subject themselves to evaluation by third parties to certify their adherence to widely accepted privacy policies and practices. In addition, policies and practices should be adapted for the particular types of personal information data being collected and/or accessed and adapted to applicable laws and standards, including jurisdiction-specific considerations that may serve to impose a higher standard. For instance, in the US, collection of or access to certain health data may be governed by federal and/or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA); whereas health data in other countries may be subject to other regulations and policies and should be handled accordingly. 
     Despite the foregoing, the present disclosure also contemplates embodiments in which users selectively block the use of, or access to, personal information data. That is, the present disclosure contemplates that hardware and/or software elements can be provided to prevent or block access to such personal information data. For example, the present technology can be configured to allow users to selectively control who can and cannot view or access the location of their tags or other location-enabled devices, and control when outside devices (e.g., devices not owned or controlled by the user) can communicate with a user&#39;s tags to provide location reports. In yet another example, users can select to limit the length of time that location information is accessible to others. In yet another example, users can configure their devices (e.g., mobile phones) not to receive, respond to, or otherwise interact with location-enabled devices such as tags. For instance, a user may configure a mobile phone to ignore instructions from tags to send location reports, display messages on behalf of the tags or the like. In addition to providing “opt in” and “opt out” options, the present disclosure contemplates providing notifications relating to the access or use of personal information. For instance, a user may be notified if another user accesses or attempts to access their location or the location of their devices or tags. 
     Moreover, it is the intent of the present disclosure that personal information data should be managed and handled in a way to minimize risks of unintentional or unauthorized access or use. Risk can be minimized by limiting the collection of data and deleting data once it is no longer needed. In addition, and when applicable, including in certain health related applications, data de-identification can be used to protect a user&#39;s privacy. De-identification may be facilitated, when appropriate, by removing identifiers, controlling the amount or specificity of data stored (e.g., collecting location data at city level rather than at an address level), controlling how data is stored (e.g., aggregating data across users), and/or other methods such as differential privacy. 
     Therefore, although the present disclosure broadly covers use of personal information data to implement one or more various disclosed embodiments, the present disclosure also contemplates that the various embodiments can also be implemented without the need for accessing such personal information data. That is, the various embodiments of the present technology are not rendered inoperable due to the lack of all or a portion of such personal information data. For example, content can be selected and delivered to users based on aggregated non-personal information data or a bare minimum amount of personal information, such as the content being handled only on the user&#39;s device or other non-personal information available to the content delivery services 
     The foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the described embodiments. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described embodiments. Thus, the foregoing descriptions of the specific embodiments described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the embodiments to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings. Also, when used herein to refer to positions of components, the terms above, below, over, under, left, or right (or other similar relative position terms), do not necessarily refer to an absolute position relative to an external reference, but instead refer to the relative position of components within the figure being referred to. 
     Objects or components that are shown or described as being at least partially embedded in or encapsulated by other objects or materials may be formed via insert molding, multi-material injection molding, or any other suitable technique. For example, in insert molding, an object may be placed into a mold, and then a moldable material may be introduced into the mold to at least partially encapsulate or at least partially embed the object in the moldable material. In multi-material injection molding, a first moldable material may be introduced into a mold (and optionally at least partially cured or hardened), followed by a second moldable material. Other techniques may also be used, such as by sewing an object into another material, positioning an object between laminate layers, or the like. 
     While many examples of functions and use cases are described with specific reference to a wirelessly locatable tag, it will be understood that the same function may be performed by any device that is configured to provide the functionality of the tags described herein. For example, a laptop computer or smartphone may have communications circuitry and other components that are similar to or provide the functions of a wirelessly locatable tag. Thus, any function performed or facilitated by a tag may also be performed or facilitated by a laptop. As one specific example, when a laptop computer is lost or misplaced, other devices in a device-location relay network may receive signals from the laptop (e.g., via Bluetooth, UWB) and send location reports to a server or host system.