Patent Description:
Millions of syringes, such as that depicted in <FIG> <FIG>, are consumed in healthcare environments every day. A typical syringe <NUM> includes a tubular body <NUM>, a plunger <NUM>, and an injection needle <NUM>. As shown in <FIG>, such a syringe <NUM> may be utilized not only to inject fluid into a patient, but also to withdraw or expel fluid out of or into a container such as a medicine bottle, vial, bag, or other drug containment system <NUM>. Indeed, due to regulatory constraints in some countries such as the United States as well as sterility maintenance concerns, upon use of a medicine bottle <NUM> with a syringe <NUM> as shown in a particular patient's environment, such medicine bottle may only be utilized with a single patient and then must be disposed of - causing significant medical waste from bottle and remaining medicine disposal, and even contributing to periodic shortages of certain critical drugs.

Referring to <FIG>, three Luer-type syringes <NUM> are depicted, each having a Luer fitting geometry <NUM> disposed distally, so that they may be coupled with other devices having similar mating geometry, such as the Luer manifold assembly <NUM> depicted in <FIG>. The Luer manifold assembly of <FIG> may be used to administer liquid drugs to the patient intravenously with or without the use of an intravenous infusion bag. The Luer fittings <NUM> of the syringes of <FIG> may be termed the "male" Luer fittings, while those of <FIG> <NUM> may be termed the "female" Luer fittings; one of the Luer interfaces may be threaded (in which case the configuration may be referred to as a "Luer lock" configuration) so that the two sides may be coupled by relative rotation, which may be combined with compressive loading. In other words, in one Luer lock embodiment, rotation, possibly along with compression, may be utilized to engage threads within the male fitting <NUM> which are configured to engage a flange on the female fitting <NUM> and bring the devices together into a fluid-sealed coupling. In another embodiment, tapered interfacing geometries may be utilized to provide for a Luer engagement using compression without threads or rotation (such a configuration may be referred to as a "slip-on" or "conical" Luer configuration). While such Luer couplings are perceived to be relatively safe for operators, there is risk of medicine spilling/leaking and parts breakage during the loading to provide a Luer coupling. The use of needle injection configurations, on the other hand, carries with it the risk of a sharp needle contacting or poking a person or structure that is not desired. For this reason, so called "safety syringes" have been developed.

One embodiment of a safety syringe <NUM> is shown in <FIG>, wherein a tubular shield member <NUM> is spring biased to cover the needle <NUM> when released from a locked position relative to the syringe body <NUM>. Another embodiment of a safety syringe <NUM> is shown in <FIG>. With such a configuration, after full insertion of the plunger <NUM> relative to the syringe body <NUM>, the retractable needle <NUM> is configured to retract <NUM>, <NUM> back to a safe position within the tubular body <NUM>, as shown in <FIG>. Such a configuration which is configured to collapse upon itself may be associated with blood spatter/aerosolization problems, the safe storage of pre-loaded energy which may possible malfunction and activate before desirable, loss of accuracy in giving full-dose injections due to residual dead space within the spring compression volume, and/or loss of retraction velocity control which may be associated with pain and patient anxiety.

Further complicating the syringe marketplace is an increasing demand for pre-filled syringe assemblies such as those depicted in <FIG>, which generally include a syringe body, or "drug enclosure containment delivery system", <NUM>, a plunger tip, plug, or stopper <NUM>, and a distal seal or cap <NUM> which may be fitted over a Luer type interface (<FIG> shows the cap <NUM> in place; <FIG> has the cap removed to illustrate the Luer interface <NUM>. Liquid medicine may reside in the volume, or medicine reservoir, <NUM> between the distal seal <NUM> and the distal end <NUM> of the stopper member <NUM>. The stopper member <NUM> may include a standard butyl rubber material and may be coated, such as with a biocompatible lubricious coating (e.g., polytetrafluoroethylene ("PTFE")), to facilitate preferred sealing and relative motion characteristics against the associated syringe body <NUM> structure and material. The proximal end of the syringe body <NUM> in <FIG> includes a conventional integral syringe flange <NUM>), which is formed integral to the material of the syringe body <NUM>. The flange <NUM> is configured to extend radially from the syringe body <NUM> and may be configured to be a full circumference, or a partial circumference around the syringe body <NUM>. A partial flange is known as a "clipped flange" while the other is known as a "full flange. " The flange is used to grasp the syringe with the fingers to provide support for pushing on the plunger to give the injection. The syringe body <NUM> preferably includes a translucent material such as a glass or polymer. To form a contained volume within the medicine chamber or reservoir <NUM>, and to assist with expulsion of the associated fluid through the needle, a stopper member <NUM> may be positioned within the syringe body <NUM>. The syringe body may define a substantially cylindrical shape (i.e., so that a plunger tip <NUM> having a circular cross sectional shape may establish a seal against the syringe body), or be configured to have other cross sectional shapes, such as an ellipse.

Such assemblies are desirable because they may be standardized and produced with precision in volume by the few manufacturers in the world who can afford to meet all of the continually changing regulations of the world for filling, packaging, and medicine/drug interfacing materials selection and component use. Such simple configurations, however, generally will not meet the new world standards for single-use, safety, auto-disabling, and anti-needle-stick. Thus certain suppliers have moved to more "vertical" solutions, such as that <NUM> featured in <FIG>, which attempts to meet all of the standards, or at least a portion thereof, with one solution; as a result of trying to meet these standards for many different scenarios, such products may have significant limitations (including some of those described above in reference to <FIG>) and relatively high inventory and utilization expenses.

Moreover, injection systems have reduced accuracy and precision as the volume of injectable fluid is reduced into the microliter range ("microdose"). In particular, removing air from the syringe body ("de-bubbling") before injection is difficult to perform accurately and precisely for such microdose injection systems.

<CIT> discloses in Figs. 21A-21B a system for injecting, according to the preamble of claim <NUM>. While this system provides technical advances, improvements remain desirable.

There is a need for injection systems which address shortcomings of currently-available configurations. In particular, there is a need for injection systems that perform (de-bubble and inject) accurately in the microliter range. It is also desirable that such syringe assemblies may utilize the existing and relatively well-controlled supply chain of conventionally delivered pre-filled cartridges and other off-the-shelf components, and the corresponding assembly machinery and personnel.

The invention is directed to a system for injecting includes a syringe body having proximal and distal ends, a syringe interior, and a syringe flange at the proximal end thereof. The system also includes an injectable fluid disposed in the syringe interior. The system further includes a stopper member disposed in the syringe interior. Moreover, the system includes a plunger member coupled to the stopper member. In addition, the system includes a finger flange removably coupled to the syringe flange, the finger flange defining a pair of side openings and a pair of bumps adjacent respective side openings. The system also includes a swing spacer rotatably coupled to the finger flange, the swing spacer defining a pair of arms, a pair of pivot pins, two pairs of slots, and a pair of indentations. The swing spacer is configured to define a distance of movement of the plunger member relative to the syringe body along a longitudinal axis of the syringe body, thereby defining a dose of the injectable fluid. The swing spacer has an aligned configuration wherein a longitudinal axis of the swing spacer is aligned with the longitudinal axis of the syringe body, and an askew configuration the longitudinal axis of the swing spacer is askew from the longitudinal axis of the syringe body. The two pairs of slots on the swing spacer include two aligned slots and two askew slots. The aligned slots are configured to interfere with the pair of bumps on the finger flange to removably retain the swing spacer in the aligned configuration. The askew slots are configured to interfere with the pair of bumps on the finger flange to removably retain the swing spacer in the askew configuration.

In one or more embodiments, the pair of pivot pins on the swing spacer are disposed in the pair of side openings on the finger flange, such that the pair of side openings and the pair of pivot pins define a hinge about which the swing spacer rotates relative to the finger flange. Respective clearances between the pair of pivot pins and respective ones of the pair of side openings allow for axial movement of the swing spacer during priming of the system. The syringe body may also include a distal needle interface configured to be coupled to a needle assembly having a needle.

The swing spacer in the aligned configuration may limit distal movement of the plunger member relative to the syringe body. The swing spacer in the askew configuration may not limit distal movement of the plunger member relative to the syringe body, such that the swing spacer is configured to define a distance of movement of the plunger member relative to the syringe body along a longitudinal axis of the syringe body, thereby defining a dose of the injectable fluid.

The pair of indentations on the swing spacer may be configured to facilitate user manipulation of the swing spacer to move the swing spacer between the aligned and askew configurations.

In one or more embodiments, the swing spacer also includes a proximal surface when the swing spacer is in the aligned configuration. The plunger member may include a stop configured to interfere with the proximal surface on the swing spacer in the aligned configuration to limit distal movement of the plunger member relative to the syringe body.

In one or more embodiments, the system has a transport configuration in which the swing spacer is in the aligned configuration and the stop on the plunger member is disposed a distance proximal of the proximal surface of the swing spacer. The system also has a primed configuration in which the swing spacer is in the aligned configuration and the stop on the plunger member is in contact with the proximal surface of the swing spacer. The system further has an injection configuration in which the swing spacer is in the askew configuration and the stop on the plunger member is disposed a distance proximal of with a proximal surface of the finger flange. Moreover, the system has a completed configuration in which the swing spacer is in the askew configuration and the stop on the plunger member is in contact with the proximal surface of the finger flange.

The aforementioned and other embodiments of the invention are described in the Detailed Description which follows.

The foregoing and other aspects of embodiments are described in further detail with reference to the accompanying drawings, in which the same elements in different figures are referred to by common reference numerals, wherein:.

In order to better appreciate how to obtain the above-recited and other advantages and objects of various embodiments, a more detailed description of embodiments is provided with reference to the accompanying drawings. It should be noted that the drawings are not drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout. It will be understood that these drawings depict only certain illustrated embodiments and are not therefore to be considered limiting of scope of embodiments.

<FIG> depict a microdose injection system <NUM> according to an embodiment. As used herein, the term "microdose" or "micro-dose" includes, but is not limited to, injections in the <NUM>-<NUM>,<NUM> microliter range. The microdose injection system <NUM> addresses the problem of injections in the microliter (e.g., <NUM>µL) volume range, which are difficult to accomplish with a standard injection system while maintaining precision (e.g., repeatability) and accuracy (e.g., proximity to desired volume). The microdose injection system <NUM> utilizes a rotatable swing spacer <NUM> and a fixed plunger member travel distance/gap to perform microdose injections.

The microdose injection system <NUM> utilizes off-the-shelf syringe bodies <NUM>, stopper members <NUM>, and needle connection members <NUM>. The microdose injection system <NUM> may also be used with off-the-shelf needle assemblies <NUM> including needle hubs <NUM> and needles <NUM>. The finger flange <NUM> in the microdose injection system <NUM> includes a pair of side openings <NUM> configured to mate with a pair of pivot pins <NUM> on a swing spacer <NUM>, as shown in <FIG>, <FIG>, and <FIG>.

The microdose injection system <NUM> includes a syringe body <NUM>, a stopper member <NUM>, a needle connection member <NUM>, a finger flange <NUM>, a plunger member <NUM>, a needle assembly <NUM>, and a swing spacer <NUM>. Many of these system components (e.g., the syringe body <NUM>, the stopper member <NUM>, and the needle connection member <NUM>) may be off-the-shelf components to utilize the existing and relatively well-controlled supply chain, and the corresponding assembly machinery and personnel. The stopper member <NUM> may have a hollow interior with an internal surface, which may have internal threads or may be un-threaded. The plunger member <NUM> is configured to have a distal end <NUM>, and a stop <NUM>. The plunger member <NUM> may be configured to include a stopper interface projection <NUM>, for interface with the stopper member <NUM>. Alternatively, the distal end of the plunger member may be smooth. The syringe body <NUM> may be an off-the-shelf <NUM> cc syringe body <NUM> to improve the accuracy of the microdose injection system <NUM>. The needle assembly <NUM> may be a commercially available, off-the-shelf needle assembly with a needle <NUM> (e.g., <NUM>-<NUM> gauge and length <NUM>-<NUM>/<NUM>"; in particular <NUM> gauge x <NUM> length). The needle assembly <NUM> may utilize Luer lock or Luer slip configurations to attach the needle assembly <NUM> to the syringe body <NUM>/needle connection member <NUM>. In some embodiments, microdose injection systems <NUM> can achieve error rates of less than ±<NUM>µL.

As shown in <FIG>, the finger flange <NUM> includes a pair of side openings <NUM> and a pair of bumps <NUM> disposed adjacent to and proximal of corresponding ones of the pair side openings <NUM>. The finger flange <NUM> also includes a proximal surface <NUM> configured to limit distal movement of the larger member <NUM> relative to the finger flange <NUM> and the syringe body <NUM> to which the finger flange <NUM> is coupled. The finger flange further includes an internal passage <NUM> configured to allow the plunger member distal end <NUM> to be inserted therethrough. The internal passage <NUM> is sized to be smaller than the stop <NUM> to prevent passage of the stop <NUM> through the internal passage <NUM>. The finger flange also includes a syringe interface <NUM> for coupling to the proximal end of the syringe body <NUM>.

As shown in <FIG>, the swing spacer <NUM> includes a pair of pivot pins <NUM> configured to be rotatably disposed in respective ones of the pair of side openings <NUM> in the finger flange such that the pair of pivot pins <NUM> and the corresponding pair of side openings <NUM> define a hinge about which the swing spacer <NUM> rotates relative to the finger flange <NUM>. The diameter of the pivot pin <NUM> is sized to be smaller than the diameter of the side openings <NUM> to allow for axial movement of the swing spacer <NUM> such that during priming of the system <NUM>, the plunger member <NUM> contacts the proximal surface <NUM> of the swing spacer <NUM>, forcing the swing spacer <NUM> distally until the distally facing surface <NUM> of the swing spacer <NUM> contacts the proximal surface <NUM> of the finger flange <NUM>. The distance between the proximal <NUM> and distal <NUM> surfaces of the swing spacer define distance <NUM> (see <FIG>), which is the size of the dose of injectable fluid to be delivered. Distance <NUM> is also the distance between the proximal surface <NUM> of the swing spacer <NUM> and the proximal surface <NUM> of the finger flange <NUM> (see <FIG>). The swing spacer <NUM> also includes respective pairs of aligned slots <NUM> and askew slots <NUM> configured to interfere with the pair of bumps <NUM> on the finger flange <NUM> removably retain the swing spacer in respective aligned and askew configurations as described herein. The swing spacer <NUM> further includes a proximal surface <NUM> configured to limit distal movement of the plunger member <NUM> relative to the finger flange <NUM> and the syringe body <NUM> to which the finger flange <NUM> is coupled when the swing spacer <NUM> is in the aligned configuration as described herein. The swing spacer <NUM> further includes a lateral slot <NUM> which is sized to allow the plunger member <NUM> distal end <NUM> to be inserted freely and is smaller than the stop <NUM> to prevent further insertion of the plunger member <NUM>. The lateral slot <NUM> is further sized to allow rotation of the swing spacer <NUM> into an askew configuration whereby the plunger member <NUM> is allowed to move distally until the stop <NUM> contacts the proximal surface <NUM> of the finger flange <NUM>. The swing spacer <NUM> is further configured to have at least one finger grip surface <NUM> disposed where it is accessible to the user's fingers for applying a force to rotate the swing spacer <NUM> from the aligned to the askew configuration.

<FIG> depicts the microdose injection system <NUM> in a transport configuration in which the microdose injection system <NUM> is delivered to a user in a packaging. In some embodiments, the microdose injection system <NUM> in the transport configuration also includes a needle cover (not shown). <FIG> also shows the swing spacer <NUM> in the aligned configuration in which a longitudinal axis of the swing spacer <NUM> is aligned with a longitudinal axis of the syringe body <NUM>. With the swing spacer <NUM> and the aligned configuration, the proximal surface <NUM> of the swing spacer <NUM> interferes with a stop <NUM> on the plunger member <NUM> to limit distal movement of the plunger member <NUM> relative to the syringe body <NUM>. In the transport configuration, the plunger member <NUM> is positioned such that the stop <NUM> is disposed a distance <NUM> proximal of the proximal surface <NUM> of the swing spacer <NUM>. This distance <NUM> is provided to allow the plunger member <NUM> to be advanced distally relative to the syringe body <NUM> to de-bubble/prime the microdose injection system <NUM> prior to injection. De-bubbling / priming the system <NUM> may include expelling air from the interior of the needle <NUM>, and/or the needle hub <NUM>, and/or the syringe body <NUM>.

<FIG> depicts the microdose injection system <NUM> in a primed configuration. The microdose injection system <NUM> is transformed from the transport configuration shown in <FIG> to the primed configuration shown in <FIG> by first positioning the microdose injection system <NUM> upright/vertical orientation to move the gases/bubbles in the syringe body <NUM> distally near the needle connecting member <NUM>, then applying a distally directed force to the plunger member <NUM> to move the plunger member <NUM> distally until the stop <NUM> on the plunger member <NUM> is in contact with the proximal surface <NUM> of the swing spacer <NUM>. The stop <NUM> on the plunger member <NUM> is configured such that closing the distance <NUM> between the stop <NUM> and the proximal and <NUM> of the swing spacer <NUM> removes all of the gases/bubbles from the syringe body <NUM> and/or the needle assembly <NUM>. The distance <NUM> can be tuned by modifying the positions of the plunger member at <NUM> and the stop <NUM> in the transport configuration to control the amount of gases/bubbles to be removed during de-bubbling.

<FIG> depicts the microdose injection system <NUM> in an injection configuration. The microdose injection system <NUM> is transformed from the primed configuration shown in <FIG> to the injection configuration shown in <FIG> by moving the swing spacer <NUM> from the aligned configuration shown in <FIG> to the askew configuration shown in <FIG>. In the askew configuration, the longitudinal axis of the swing spacer <NUM> is askew (e.g., about <NUM>°) from the longitudinal axis of the syringe body <NUM>. As shown in <FIG>, the swing spacer <NUM> and the askew configuration does not interfere with distal movement of the plunger member <NUM> relative to the syringe body <NUM>. Moving the swing spacer <NUM> from the aligned configuration to the askew configuration uncovers a distance <NUM> between the stop <NUM> on the plunger member <NUM> and the proximal surface <NUM> of the finger flange <NUM>. The distance between the proximal <NUM> and distal <NUM> surfaces of the swing spacer define the plunger rod distance <NUM> (see <FIG> and <FIG>), which is the size of the dose of injectable fluid to be delivered by the microdose injection system <NUM>. In the embodiment depicted in <FIG>, the dose of injectable fluid may be <NUM>µL. In other embodiments, the dose may be <NUM> to <NUM>µL.

<FIG> depicts the microdose injection system <NUM> in a completed configuration. The microdose injection system <NUM> is transformed from the injection configuration shown in <FIG> to the completed configuration shown in <FIG> by first positioning a tip of the needle <NUM> coupled to the needle connecting member <NUM> in the injection targeted (e.g., patient), then applying a distally directed force to the plunger member <NUM> to move the plunger member <NUM> distally until the stop <NUM> on the plunger member <NUM> is in contact with the proximal surface <NUM> of the finger flange <NUM>. The stop <NUM> on the plunger member <NUM> and the swing spacer <NUM> are configured such that closing the distance <NUM> between the stop <NUM> and the proximal surface <NUM> of the finger flange <NUM> delivers a predefined dose of injectable fluid from the syringe body <NUM>. The distance <NUM> can be tuned by modifying the modifying the positions of the plunger member at <NUM> and the stop <NUM> and the size of the swing spacer <NUM> to control the size of the dose of injectable fluid.

After injection, a needle <NUM> attached to the needle connecting member <NUM> may be retracted such that the sharp tip thereof is contained within the needle assembly <NUM> to provide a safe microdose injection system.

<FIG> and <FIG> depict a microdose injection system <NUM> in the primed and injection configurations according to some other embodiments. The swing spacer <NUM> in the microdose injection system <NUM> is longer than the swing spacer <NUM> and the microdose injection system <NUM> depicted in <FIG>. The distance <NUM> between the proximal and distal surfaces of the swing spacer <NUM> is greater than the distance <NUM> depicted in <FIG> and <FIG>. Accordingly, the microdose injection system <NUM> is configured to deliver a larger (e.g., <NUM>µL) dose of an injectable fluid.

While various embodiments have been described with specific connectors (e.g., slip and Luer), these embodiments can be used with any known injection system connectors. While various embodiments have been described with staked needles and needle connectors, these embodiments can be used with any known permanently coupled needle or needle connector system.

Various exemplary embodiments of the invention are described herein. Reference is made to these examples in a non-limiting sense. They are provided to illustrate more broadly applicable aspects of the invention. Various changes may be made to the invention described and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s) to the objective(s), and scope of the present invention. Further, as will be appreciated by those with skill in the art that each of the individual variations described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present inventions. All such modifications are intended to be within the scope of claims associated with this disclosure.

Any of the devices described for carrying out the subject diagnostic or interventional procedures may be provided in packaged combination for use in executing such interventions. These supply "kits" may further include instructions for use and be packaged in sterile trays or containers as commonly employed for such purposes.

The invention discloses methods that may be performed using the subject devices. The methods may comprise the act of providing such a suitable device. Such provision may be performed by the end user. In other words, the "providing" act merely requires the end user obtain, access, approach, position, set-up, activate, power-up or otherwise act to provide the requisite device in the subject method. Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as in the recited order of events.

Exemplary aspects of the invention, together with details regarding material selection and manufacture have been set forth above. As for other details of the present invention, these may be appreciated in connection with the above-referenced patents and publications as well as generally known or appreciated by those with skill in the art. For example, one with skill in the art will appreciate that one or more lubricious coatings (e.g., hydrophilic polymers such as polyvinylpyrrolidone-based compositions, fluoropolymers such as tetrafluoroethylene, PTFE, hydrophilic gel or silicones) may be used in connection with various portions of the devices, such as relatively large interfacial surfaces of movably coupled parts, if desired, for example, to facilitate low friction manipulation or advancement of such objects relative to other portions of the instrumentation or nearby tissue structures. The same may hold true with respect to method-based aspects of the invention in terms of additional acts as commonly or logically employed.

In addition, though the invention has been described in reference to several examples optionally incorporating various features, the invention is not to be limited to that which is described or indicated as contemplated with respect to each variation of the invention. Various changes may be made to the invention described and equivalents (whether recited herein or not included for the sake of some brevity) may be substituted without departing from the scope of the invention. In addition, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention.

Without the use of such exclusive terminology, the term "comprising" in claims associated with this disclosure shall allow for the inclusion of any additional element--irrespective of whether a given number of elements are enumerated in such claims, or the addition of a feature could be regarded as transforming the nature of an element set forth in such claims. Except as specifically defined herein, all technical and scientific terms used herein are to be given as broad a commonly understood meaning as possible while maintaining claim validity.

Claim 1:
A system (<NUM>) for injecting, comprising:
a syringe body (<NUM>) having proximal and distal ends, a syringe interior, and a syringe flange at the proximal end thereof;
an injectable fluid disposed in the syringe interior;
a stopper member (<NUM>) disposed in the syringe interior;
a plunger member (<NUM>) coupled to the stopper member (<NUM>);
a finger flange (<NUM>) removably coupled to the syringe flange; and
a swing spacer (<NUM>) rotatably coupled to the finger flange (<NUM>), the swing spacer (<NUM>) defining a pair of arms,
wherein the swing spacer (<NUM>) is configured to define a distance of movement of the plunger member (<NUM>) relative to the syringe body (<NUM>) along a longitudinal axis of the syringe body (<NUM>), thereby defining a dose of the injectable fluid,
characterized in that
the finger flange (<NUM>) defines a pair of side openings (<NUM>) and a pair of bumps (<NUM>) adjacent respective side openings (<NUM>);
the swing spacer (<NUM>) defines a pair of pivot pins (<NUM>), two pairs of slots (<NUM>, <NUM>), and a pair of indentations (<NUM>);
the swing spacer (<NUM>) has an aligned configuration wherein a longitudinal axis of the swing spacer (<NUM>) is aligned with the longitudinal axis of the syringe body (<NUM>), and an askew configuration wherein the longitudinal axis of the swing spacer (<NUM>) is askew from the longitudinal axis of the syringe body (<NUM>),
the two pairs of slots (<NUM>, <NUM>) on the swing spacer (<NUM>) comprises two aligned slots (<NUM>) and two askew slots (<NUM>),
the aligned slots (<NUM>) are configured to interfere with the pair of bumps (<NUM>) on the finger flange (<NUM>) to removably retain the swing spacer (<NUM>) in the aligned configuration, and
the askew slots (<NUM>) are configured to interfere with the pair of bumps (<NUM>) on the finger flange (<NUM>) to removably retain the swing spacer (<NUM>) in the askew configuration.