Patent Publication Number: US-2021178102-A1

Title: Dual slider headgear adjustment system with easy pull tabs and patient interface device including same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application claims the priority benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 62/948,895 filed on Dec. 17, 2019, the contents of which are herein incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to headgear for use in securing patient interface devices to the head of a patient and, more particularly, to adjustment systems for use in adjusting such headgear to fit the head of a patient. The present invention further pertains to strap assemblies for use in such adjustment systems. 
     2. Description of the Related Art 
     Many individuals suffer from disordered breathing during sleep. Sleep apnea is a common example of such sleep disordered breathing suffered by millions of people throughout the world. One type of sleep apnea is obstructive sleep apnea (OSA), which is a condition in which sleep is repeatedly interrupted by an inability to breathe due to an obstruction of the airway; typically the upper airway or pharyngeal area. Obstruction of the airway is generally believed to be due, at least in part, to a general relaxation of the muscles which stabilize the upper airway segment, thereby allowing the tissues to collapse the airway. Another type of sleep apnea syndrome is a central apnea, which is a cessation of respiration due to the absence of respiratory signals from the brain&#39;s respiratory center. An apnea condition, whether obstructive, central, or mixed, which is a combination of obstructive and central, is defined as the complete or near cessation of breathing, for example a 90% or greater reduction in peak respiratory air-flow. 
     Those afflicted with sleep apnea experience sleep fragmentation and complete or nearly complete cessation of ventilation intermittently during sleep with potentially severe degrees of oxyhemoglobin desaturation. These symptoms may be translated clinically into extreme daytime sleepiness, cardiac arrhythmias, pulmonary-artery hypertension, congestive heart failure and/or cognitive dysfunction. Other consequences of sleep apnea include right ventricular dysfunction, carbon dioxide retention during wakefulness, as well as during sleep, and continuous reduced arterial oxygen tension. Sleep apnea sufferers may be at risk for excessive mortality from these factors as well as by an elevated risk for accidents while driving and/or operating potentially dangerous equipment. 
     Even if a patient does not suffer from a complete or nearly complete obstruction of the airway, it is also known that adverse effects, such as arousals from sleep, can occur where there is only a partial obstruction of the airway. Partial obstruction of the airway typically results in shallow breathing referred to as a hypopnea. A hypopnea is typically defined as a 50% or greater reduction in the peak respiratory air-flow. Other types of sleep disordered breathing include, without limitation, upper airway resistance syndrome (UARS) and vibration of the airway, such as vibration of the pharyngeal wall, commonly referred to as snoring. 
     It is well known to treat sleep disordered breathing by applying a continuous positive air pressure (CPAP) to the patient&#39;s airway. This positive pressure effectively “splints” the airway, thereby maintaining an open passage to the lungs. It is also known to provide a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient&#39;s breathing cycle, or varies with the patient&#39;s breathing effort, to increase the comfort to the patient. This pressure support technique is referred to as bi-level pressure support, in which the inspiratory positive airway pressure (IPAP) delivered to the patient is higher than the expiratory positive airway pressure (EPAP). It is further known to provide a positive pressure therapy in which the pressure is automatically adjusted based on the detected conditions of the patient, such as whether the patient is experiencing an apnea and/or hypopnea. This pressure support technique is referred to as an auto-titration type of pressure support, because the pressure support device seeks to provide a pressure to the patient that is only as high as necessary to treat the disordered breathing. 
     Pressure support therapies as just described involve the placement of a patient interface device including a mask component having a soft, flexible sealing cushion on the face of the patient. The mask component may be, without limitation, a nasal mask that covers the patient&#39;s nose, a nasal/oral mask that covers the patient&#39;s nose and mouth, or a full face mask that covers the patient&#39;s face. Such patient interface devices may also employ other patient contacting components, such as forehead supports, cheek pads and chin pads. The patient interface device is connected to a gas delivery tube or conduit and interfaces the pressure support device with the airway of the patient, so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient. 
     The patient interface device is typically secured to the patient&#39;s head by a headgear component. Headgear components typically include one or more straps that wrap partially, or completely around the back of the patient&#39;s head. Hook and loop fastening arrangements are commonly used to provide for adjustability of headgear components, however such arrangements limit material selection and typically require use of a lamination. An alternative approach is the use of elastic materials in headgear to provide for deformation of the headgear when installing or removing from the patient&#39;s head, however such arrangements tend to stretch out over time and do not offer true adjustability. Some sliding adjustment arrangements are known, however, such arrangements are typically difficult to adjust or generally only adjustable in a single direction. Accordingly, there is room for improvement in adjustment systems for use in headgear for securing patient interface devices to the head of a patient. 
     SUMMARY OF THE INVENTION 
     As one aspect of the invention, an adjustment system for use in a headgear for securing a patient interface device to the head of a patient is provided. The adjustment system comprises: a first strap assembly; and a second strap assembly positioned 180 degrees with respect to the first assembly and entwined with the first strap assembly. Each of the first strap assembly and the second strap assembly comprises: a slider having a body comprising: a first slot defined in the body; and a second slot defined in the body parallel to the first slot, wherein the first slot and the second slot are each defined in-part by an elongate central portion of the body that is disposed between, and extends along the length of both the first slot and the second slot, wherein the first slot is further defined by an elongate first end portion of the body that extends along the length of the first slot and is disposed parallel to the central portion, wherein the second slot is further defined by an elongate second end portion of the body that extends along the length of the second slot and is disposed parallel to the central portion on the opposite side thereof from the first end portion, wherein the central portion, the first end portion, and the second end portion are coupled together at a top end of the body and at a bottom end of the body via other portions of the body, thus forming the first slot and the second slot; a strap portion having a first end coupled to the second end portion of the slider and an opposite second end structured to be coupled to one or more of the patient interface device or another portion of the headgear; and a tab coupled to the first end portion of the slider, the tab being structured to be grasped by the patient. 
     The tab of each of the first strap assembly and the second strap assembly may comprise an opening defined therein. 
     In each of the first strap assembly and the second strap assembly, the tab may be coupled to the first end portion of the slider by an end portion of the tab that: extends through the first slot of the slider, is folded around the first end portion of the body back onto an adjacent part of the tab, and is secured to the adjacent portion of the tab. 
     In each of the first strap assembly and the second strap assembly, the tab may be coupled to the slider via over-molding of a portion of the tab over a portion of the slider. 
     In each of the first strap assembly and the second strap assembly the tab and the slider may be formed as portions of a single unitary member. 
     In each of the first strap assembly and the second strap assembly the slider may be coupled to the tab via over-molding of a portion of the slider over a portion of the tab and over-molding of another portion of the slider over a portion of the strap portion. 
     The first strap assembly and the second strap assembly may be entwined such that: the strap portion of the first strap assembly extends from slider of the first strap assembly, along the strap portion of the second strap assembly before passing in front of the second end portion of the slider of the second strap assembly; the strap portion of the first strap assembly then passes rearward through the second slot of the slider of the second strap assembly, wraps partially around the central portion of the slider of the second strap assembly, and then passes forward through first slot of the slider of the second strap assembly; the strap portion of the first strap assembly then passes in front of the first end portion of the slider of the second strap assembly, passes rearward through the opening of the tab of the second strap assembly, and then extends to an end structured to be coupled with the one or more of the patient interface device or another portion of the headgear; the strap portion of the second strap assembly extends from the slider of the second strap assembly, along the strap portion of the first strap assembly before passing behind the second end portion of the slider of the first strap assembly; the strap portion of the second strap assembly then passes forward through the second slot of the slider of the first strap assembly, wraps partially around the central portion of the slider of the first strap assembly, and then passes rearward through the first slot of the slider of the first strap assembly; and the strap portion of the second strap assembly then passes behind the first end portion of the slider of the first strap assembly, behind the tab of the first strap assembly without passing through the opening of the first strap assembly, and then extends to another end structured to be coupled with the one or more of the patient interface device or another portion of the headgear. 
     As another aspect of the invention, a respiratory interface system for providing a regimen of respiratory therapy to a patient comprises: a patient interface device that is structured to communicate a flow of breathing gas received to an airway of the patient; and a headgear coupled to the patient interface device, the headgear being structured to secure the patient interface device to the head of the patient, the headgear including an adjustment system such as described herein. 
     As yet a further aspect of the invention, a strap assembly for an adjustment system for use in a headgear for securing a patient interface device to the head of a patient is provided. The strap assembly comprises: a slider having a body comprising: a first slot defined in the body; and a second slot defined in the body parallel to the first slot, wherein the slot and the second slot are each defined in-part by an elongate central portion of the body that is disposed between, and extends along the length of both the first slot and the second slot, wherein the first slot is further defined by an elongate first end portion of the body that extends along the length of the first slot and is disposed parallel to the central portion, wherein the second slot is further defined by an elongate second end portion of the body that extends along the length of the second slot and is disposed parallel to the central portion on the opposite side thereof from the first end portion, wherein the central portion, the first end portion, and the second end portion are coupled together at a top end of the body and at a bottom end of the body via other portions of the body, thus forming the first slot and the second slot; a strap portion having a first end coupled to the second end portion of the slider and an opposite second end structured to be coupled to one or more of the patient interface device or another portion of the headgear; and a tab coupled to the first end portion of the slider, the tab being structured to be grasped by the patient. 
     The tab may comprise an opening defined therein. 
     The tab may be coupled to the first end portion of the slider by one of: an end portion of the tab that: extends through the first slot of the slider, is folded around the first end portion of the body back onto an adjacent part of the tab, and is secured to the adjacent portion of the tab; or via over-molding of a portion of the tab over a portion of the slider. 
     The tab and the slider may be formed as portions of a single unitary member. 
     These and other objects, features, and characteristics of the present invention, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a partially schematic depiction of a respiratory interface system for use in providing a flow of positive pressure breathing gas to the airway of a patient in accordance with one example embodiment of the present invention, shown with a patient interface device thereof disposed on the head of a patient and secured thereto by a headgear having an adjustment system in accordance with one example embedment of the present invention; 
         FIG. 2  is rear view of the head of the patient of  FIG. 1  with the patient interface disposed on the head of the patient showing the headgear; 
         FIGS. 3A-3D  are elevation views of strap assemblies of adjustment systems in accordance with some example embodiments of the present invention; 
         FIG. 4  is an exploded view of the strap assembly of  FIG. 3A ; 
         FIGS. 5A-5C  are views of strap assemblies of adjustment systems in accordance with some example embodiments of the present invention; 
         FIG. 6  is a front elevation view of two of the strap assemblies of  FIG. 3A  shown interlaced forming an adjustment system in accordance with one example embodiment of the present invention; 
         FIG. 7  is a sectional view of the adjustment system of  FIG. 6  taken along line  7 - 7  of  FIGS. 6 ; and 
         FIG. 8  is another front elevation view of the adjustment system of  FIG. 6  shown with the relative positioning of the two strap assemblies adjusted to a second positioning corresponding to a tightening of the adjustment system. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     As used herein, the singular form of “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. As used herein, the statement that two or more parts or components are “coupled” shall mean that the parts are joined or operate together either directly or indirectly, i.e., through one or more intermediate parts or components, so long as a link occurs. As used herein, “directly coupled” means that two elements are directly in contact with each other. As used herein, “fixedly coupled” or “fixed” means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other. 
     Directional phrases used herein, such as, for example and without limitation, top, bottom, left, right, upper, lower, front, back, and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein. 
     As used herein, the statement that two or more parts or components “engage” one another shall means that the parts exert a force against one another either directly or through one or more intermediate parts or components. 
     As used herein, the word “unitary” means a component is created as a single piece or unit. That is, a component that includes pieces that are created separately and then coupled together as a unit is not a “unitary” component or body. 
     As used herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality). 
     As used herein, a “coupling assembly” includes two or more couplings or coupling components. The components of a coupling or coupling assembly are generally not part of the same element or other component. As such the components of a “coupling assembly” may not be described at the same time in the following description. 
     As used herein, “correspond” indicates that two structural components are sized and shaped to be similar to each other and may be coupled with a minimum amount of friction. Thus, an opening which “corresponds” to a member is sized slightly larger than the member so that the member may pass through the opening with a minimum amount of friction. This definition is modified if the two components are said to fit “snugly” together or “snuggly correspond.” In that situation, the difference between the size of the components is even smaller whereby the amount of friction increases. If the element defining the opening and/or the component inserted into the opening is/are made from a deformable or compressible material, the opening may even be slightly smaller than the component being inserted into the opening. This definition is further modified if the two components are said to “substantially correspond.” “Substantially correspond” means that the size of the opening is very close to the size of the element inserted therein. That is, not so close as to cause substantial friction, as with a snug fit, but with more contact and friction than a “corresponding fit,” i.e. a “slightly larger” fit. 
     A respiratory interface system  2  adapted to provide a regimen of respiratory therapy to a patient P according to one exemplary embodiment of the present invention is shown in  FIG. 1 . Respiratory interface system  2  includes a pressure generating device  4  (shown schematically), and a delivery conduit  6  (shown schematically) fluidly coupled to a patient interface device  8 . Pressure generating device  4  is structured to generate a flow of positive pressure breathing gas and may include, without limitation, ventilators, constant pressure support devices (such as a continuous positive airway pressure device, or CPAP device), variable pressure devices (e.g., BiPAP®, Bi-Flex®, or C-Flex™ devices manufactured and distributed by Philips Respironics of Murrysville, Pa.), and auto-titration pressure support devices. Delivery conduit  6  is structured to communicate the flow of breathing gas from pressure generating device  4  to patient interface device  8 , and patient interface device  8  is structured to further communicate the flow of breathing gas received from conduit  6  to an airway of patient P. Delivery conduit  6  and patient interface device  8  are often collectively referred to as a patient circuit. Patient interface device  8  includes a tubing assembly  10  and a mask  12  fluidly coupled to tubing assembly  10 . It is to be appreciated that patient interface device  8  and components thereof are provided for example purposes only and that embodiments of the present invention may be readily employed with various other patient interface devices without varying from the scope of the present invention. 
     Continuing to refer to  FIG. 1 , as well as to  FIG. 2 , patient interface device  8  is generally secured to the head of patient P via a headgear  14  having an adjustment system  16  ( FIG. 2 ) in accordance with one example embodiment of the present invention. In the one example embodiment shown in  FIGS. 1 and 2 , headgear  14  is coupled to patient interface device  8  at two different locations (not numbered) along tubing assembly  10  on different sides of the head of patient P, however, it is to be appreciated that adjustment system  16  may be utilized in various other headgear arrangements without varying from the scope of the present invention. 
     Continuing to refer to  FIG. 2 , adjustment system  16  includes a first strap assembly  18  and a second strap assembly  20  entwined with each other, as discussed in detail further below. As shown in  FIGS. 3A and 4 , first strap assembly  18  includes a strap portion  22 , a slider  24 , and a tab  25  that are coupled together in series such that strap portion  22  and tab  25  are not directly coupled together but instead are coupled together indirectly via slider  24 . Such coupling of strap portion  22 , slider  24  and tab  25  is discussed in greater detail below. 
     Strap portion  22  is an elongate, generally thin element formed from a highly flexible material, e.g., without limitation, knit or woven fabrics, laminate materials, or any other suitable material or combination of materials. 
     Slider  24  includes a body  26  generally of a planar shape that is formed from a rigid material (e.g., coated metal, plastic) or a semi-rigid material (e.g., stiff thermoplastic elastomer). Slider  24  includes a first slot  28  and a second slot  30  defined parallel to each other in body  26 . More particularly, first and second slots  28  and  30  are each defined in-part by an elongate central portion  32  of body  26  that is disposed between, and extends along the length of both first slot  28  and second slot  30 . First slot  28  is further defined by an elongate first end portion  34  of body  26  that extends along the length of first slot  28  and is disposed parallel to central portion  32 . Second slot  30  is further defined by an elongate second end portion  36  of body  26  that extends along the length of second slot  30  and is disposed parallel to central portion  32  on the opposite side thereof from first end portion  34 . Central portion  32 , first end portion  34 , and second end portion  36  are coupled together at a top end  26 A of body  26  and at a bottom end  26 B via other portions (not numbered) of body  26 , thus forming first and second slots  28  and  30 . 
     Tab  25  is structured to be grasped by patient P for use in adjusting adjustment system  16 . Tab  25  may be formed from a wide variety of materials without varying from the scope of the present invention. In embodiments in accordance with some examples of the present invention, tab  25  has been formed from non-stretch woven or knit materials (e.g., nylon), flexible polymers (e.g., TPE, silicone, rubber), as well as very thin (e.g., less than 1 mm thickness) rigid polymers (e.g., PP, PC). In the one example shown in  FIGS. 2 and 3A , tab  25  includes a large opening  40  defined therein, the purpose of which is described further below. 
     Referring now to  FIGS. 3A-3D , some examples of how strap portion  22 , slide  24  and tab  26  may be coupled will be described. In the one example first strap assembly  18  shown in  FIG. 3A , strap portion  22  is coupled to slider  24  via an end portion  22 A of strap portion  22  that extends through second slot  30  of slider  24  and is folded around second end portion  36  of body  26  back onto the adjacent part of strap portion  22 . End portion  22 A is secured back onto strap portion  22  via stitching or any other suitable arrangement. Similarly, an end portion  25 A of tab  25  is coupled to slider  24  via an end portion  25 A of tab  25  that extends through first slot  28  of slider  24  and is folded around first end portion  34  of body  26  back onto the adjacent part of tab  25 . End portion  25 A is secured back onto tab  25  via stitching or any other suitable arrangement. 
       FIG. 3B  shows a first strap assembly  118  in accordance with one example embodiment of the present invention in which strap portion  22  is coupled to slider  24  in the same manner as the arrangement of  FIG. 3A , however, tab  125  is coupled to slider  24  via over-molding of the tab  125  onto slider  24 . 
       FIG. 3C  shows a first strap assembly  218  in accordance with one example embodiment of the present invention in which a tab  225  and a slider  224  are formed as portions of a single unitary member and thus are coupled by virtue of them being formed together. In such example, strap portion  22  is coupled to slider  224  thereof in the same manner as the arrangements of  FIGS. 3A and 3B . 
       FIG. 3D  shows an example first strap assembly  318  in accordance with one example embodiment of the present invention in which a tab  325  is coupled to a strap portion  322  via a slider  324  which is over-molded onto both of tab  325  and strap portion  322 . 
     In addition to there being multiple ways in which the tab and slider components of a strap assembly may be coupled, there is also multiple ways in which the tab may engage the slider in a strap assembly. For example,  FIG. 5A  shows a strap assembly  418  in accordance with one example embodiment of the present invention wherein a tab  425  engages slider  24  along generally the entirety of first end portion  34  thereof. As another example,  FIG. 5B  shows a strap assembly  518  in accordance with one example embodiment of the present invention wherein a tab  525  engages slider  24  only at a central area of first end portion  34  thereof away from top and bottom ends  26 A and  26 B thereof. As yet another example,  FIG. 5C  shows a strap assembly  618  in accordance with one example embodiment of the present invention wherein a tab  625  engages slider  24  only at distal ends of first end portion  34  thereof near top and bottom ends  26 A and  26 B thereof. 
     Second strap assembly  20  is of the same arrangement as first strap assembly  18  and thus the description thereof will not be repeated herein. However, in the description of adjustment system  16  that follows, elements of second strap assembly  20  are referred to by the same reference numerals as first strap assembly  18 , previously discussed, however, such reference numerals for second strap assembly  20  include prime added thereto. For example, the strap portion of first strap assembly  18  is identified by reference numeral “ 22 ”, while the strap portion of second strap assembly  20  is identified by reference numeral “ 22 ”. 
     Referring now to  FIGS. 6-8 , adjustment system  16  will now be described. As previously discussed, adjustment system  16  includes first strap assembly  18  and second strap assembly  20 . First strap assembly  18  and second strap assembly  20  are positioned 180 degrees with respect to each other and entwined with each other. More particularly, first and second strap assemblies  18  and  20  are arranged such that strap portion  22  of first strap assembly  18  extends (to the right in  FIGS. 6 and 7 ) from slider  24 , along (in front of) strap portion  22 ′ of second strap assembly  20  before passing in front of second end portion  36 ′ of slider  24 ′ of second strap assembly  20 . Strap portion  18  then passes rearward through second slot  30 ′ of slider  24 ′, wraps partially around central portion  32 ′ of slider  24 ′, and then passes forward through first slot  28 ′ of slider  24 ′. Strap portion  22  then passes in front of first end portion  34 ′ of slider  24 ′, passes rearward through opening  40 ′ of tab  25 ′, and then extends to a connection with patient interface device  8 . Similarly, strap portion  22 ′ of second strap assembly  20  extends (to the left in  FIGS. 6 and 7 ) from slider  24 , along (behind) strap portion  22  of first strap assembly  18  before passing behind second end portion  36  of slider  24  of first strap assembly  20 . Strap portion  22 ′ then passes forward through second slot  30  of slider  24 , wraps partially around central portion  32  of slider  24 , and then passes rearward through first slot  28  of slider  24 . Strap portion  22 ′ then passes behind first end portion  34  of slider  24 , behind tab  25  (without passing through opening  40 ), and then extends to another connection with patient interface device  8 . 
     In the one example embodiment shown in  FIGS. 2, 6 and 8 , adjustment system  16  provides for headgear  14  to be readily tightened to secure patient interface device  8  to the head of patient P. Such adjustment is accomplished simply by grasping each of tabs  25  and  25 ′ and pulling them away from each other (i.e., pulling tab  25  to the left and tab  25 ′ to the right in the views shown in  FIGS. 2, 6 and 8 . For example, starting with first and second trap assemblies  18  and  20  positioned as shown in  FIG. 6 , the centers of sliders  24  and  24 ′ are spaced a distance D 1 .  FIG. 8  shows a second positioning of first and second strap assemblies  18  and  20  after tabs  25  and  25 ′ have been pulled away from each other, thus causing sliders  24  and  24 ′ to thus be separated by a second distance D 2 , which thus reduces the overall length of adjustment system  16  by the length D 2 -D 1 . To return first and second strap assemblies  18  and  20  back to the positioning of  FIG. 6 , a user grasps the top and bottom ends  26 A and  26 B of each slider  24  and  24 ′ and urges sliders  24  and  24 ′ toward each other, thus loosening headgear  14 . 
     It is to be appreciated that embodiments of the present invention provide for adjustment systems that allow for the use of materials other than laminated un-broken loop fabric/Velcro. For example, without limitation, athletic knits may be employed while still having the ability to adjust. It is also to be appreciated that an adjustment system such as described herein is symmetric, and thus tightens evenly, as opposed to pulling to one side. The large grip pull tabs are easily grasped, and the openings defined therein are easily gripped by at least one finger of a user. The redundant sliders provide for less of a chance for the adjustment to slip. The symmetric design is economically efficient for manufacturing. 
     In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word “comprising” or “including” does not exclude the presence of elements or steps other than those listed in a claim. In a device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The word “a” or “an” preceding an element does not exclude the presence of a plurality of such elements. In any device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain elements are recited in mutually different dependent claims does not indicate that these elements cannot be used in combination. 
     Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.