US 9414635

US Patent 9414635, titled "Biomechanics aware helmet," was issued to Brainguard Technologies Inc. on August 16, 2016, from an application filed on July 24, 2015. The sole inventor listed is Robert T. Knight.

Abstract:
The patent describes protective gear, such as a helmet, featuring an outer shell layer connected to a middle shell layer via an outer energy and impact transformer layer. This middle layer is further connected to an inner shell layer through an inner energy and impact transformer layer. These transformer layers are designed to flexibly connect the shell layers, allowing them to move and slide relative to each other to absorb impact forces, rotational forces, and shear forces. The transformer layers can be made from materials like gels, fluids, electro-rheological elements, or magneto-rheological elements, protecting users from impact, penetrative, rotational, and shear forces.

Independent Claims Overview:

• Claim 1 (Helmet): This claim describes a helmet with an outer shell layer and an inner shell layer. The key feature is a "shear mechanism" that connects these two layers, allowing the outer shell to slide relative to the inner shell. This shear mechanism incorporates a first energy transformer with a material that absorbs or dissipates energy. The inner shell layer is designed to conform to a human head, and a chin strap is attached to this inner layer to keep it in place during rotational impact, even as the outer shell is permitted to slide.
• Claim 9 (Protective Gear): Similar to Claim 1, this claim broadly covers "protective gear" (which could include items beyond just helmets, as mentioned in the abstract). It includes an outer shell layer and an "inner conforming layer" (equivalent to the inner shell layer in Claim 1) that connects to the outer layer via a shear mechanism. This mechanism allows relative sliding and includes a first energy transformer with an absorptive/dissipative material. The inner conforming layer is shaped to fit a human head, and a chin strap is attached to it to maintain its position during rotational force impacts while the outer layer slides.
• Claim 17 (Helmet): This claim is essentially identical to Claim 9 but specifically refers to the protective gear as a "helmet." It comprises an outer shell layer and an inner conforming layer connected by a shear mechanism that enables relative sliding of the outer shell. This shear mechanism includes a first energy transformer with an absorptive/dissipative material. The inner conforming layer conforms to a human head, and a chin strap is attached to it to secure its position on the head during rotational force impacts while the outer shell layer is allowed to slide.

Litigation:
As of April 26, 2026, Google Patents indicates that the patent family has litigation, specifically mentioning a PTAB case IPR2025-01032 which was filed but not instituted (procedural), and a U.S. case filed in the California Central District Court, case number 8:24-cv-02652. No specific dockets for the U.S. Court of Appeals for the Federal Circuit (CAFC) for 2026 relating directly to US9414635 were found in the provided search results.

As a patent attorney, I have identified the following known litigation involving US patent 9414635:

• Case: IPR2025-01032

  • Plaintiff(s): Unified Patents
  • Defendant(s): Brainguard Technologies Inc. (implied, as the assignee of US9414635)
  • Jurisdiction: Patent Trial and Appeal Board (PTAB)
  • Case Number: IPR2025-01032
  • Filing Date: Not explicitly stated, but the IPR number indicates a filing in 2025.
  • Outcome or Current Status: Not Instituted - Procedural

• Case: 8:24-cv-02652

  • Plaintiff(s): Not explicitly stated in the provided snippet, but Unified Patents is the source of the litigation data.
  • Defendant(s): Not explicitly stated in the provided snippet.
  • Jurisdiction: California Central District Court
  • Case Number: 8:24-cv-02652
  • Filing Date: Not explicitly stated, but the case number indicates a filing in 2024.
  • Outcome or Current Status: Litigation is ongoing.

Proceedings overview

There is one AIA trial proceeding on file for US patent 9414635, which resulted in a discretionary denial of institution. This means the patent's claims have not been reviewed on the merits by the PTAB and remain sustained, presenting a hardened defensive posture for the patent owner.

IPR2025-01032 — REVELYST SALES LLC et al. v. Brainguard Technologies Inc.

• Type: Inter Partes Review
• Filed: 2025-07-09
• Status: Discretionary Denial – The PTAB declined to institute a trial on the merits.
• Judge panel: The specific judge panel for this discretionary denial is not publicly available in the provided search results.
• Petition grounds: The specific claims challenged, prior art cited, and statutory bases (§ 102 / § 103 / § 112) for the petition are not publicly available in the provided search results.
• Institution decision: Denied institution. While the exact date of the decision and specific reasoning for this IPR are not provided in the search results, discretionary denials in mid-to-late 2025 often centered on the "settled expectations" of the parties, particularly concerning the patent's age, and an evaluation of the Fintiv factors related to parallel district court litigation and PTAB workload management. The USPTO implemented a new bifurcated review process in March 2025, where discretionary considerations are assessed before the merits.
• Final Written Decision: No Final Written Decision was issued because the petition for institution was denied.
• Settlement / termination: This proceeding was terminated by the denial of institution, rather than a settlement.
• Appeal: No appeal to the Federal Circuit was applicable, as no trial was instituted and no final written decision on the merits was issued.
• Defensive value: The denial of institution means that all claims of US9414635 challenged in this IPR remain unadjudicated by the PTAB and therefore presumptively valid. For a defendant facing assertion of this patent, this indicates that an IPR challenge on the same or similar grounds would face significant hurdles given the precedent of discretionary denial, potentially strengthening the patent owner's position.

Strategic summary

All claims of US9414635 remain SUSTAINED and UNTESTED by the PTAB on their merits, as the single IPR filed against the patent, IPR2025-01032, resulted in a discretionary denial of institution. This means no claims were invalidated by the PTAB.

Regarding the estoppel landscape, since the PTAB did not institute a trial, the petitioner, REVELYST SALES LLC et al., and their privies are not statutorily estopped under § 315(e)(2) from raising invalidity grounds that were raised or reasonably could have been raised in a district court action. However, the discretionary denial itself sets a precedent that could make it difficult for the same petitioner or related parties to successfully file another IPR on similar grounds against this patent. The grounds for discretionary denial, such as "settled expectations" due to the patent's age, could be a recurring barrier.

The pattern signals indicate limited PTAB activity for US9414635, with only one IPR filing that did not proceed to trial. The involvement of "Unified Patents" as the petitioner in the Google Patents listing is notable [cite: https://patents.google.com/patent/US9414635/en], suggesting a defensive aggregator attempted to challenge the patent. The discretionary denial, especially if based on factors like "settled expectations" or Fintiv considerations, suggests a current environment at the PTAB that may be less hospitable to challenges against older patents or those involved in parallel district court litigation.

Recommended next steps

Since no claims of US9414635 have been invalidated by the PTAB, any infringement theory built on the existing claims remains robust from a PTAB validity perspective.

For a defendant considering a challenge to this patent, it is crucial to understand the specific reasoning behind the discretionary denial in IPR2025-01032. Although the detailed decision is not available in the provided search results, the general trend of discretionary denials by the PTAB in late 2025 often involved the "settled expectations" doctrine and consideration of factors related to parallel district court litigation, as formalized by the USPTO's interim process. Future IPR petitions would need to address these discretionary factors carefully.

Currently, there are no active PTAB proceedings pending for US9414635. The absence of further PTAB challenges after a discretionary denial can be a signal that potential petitioners view the pathway to institution as challenging.

Inventors

• Robert T. Knight (employer not determinable from patent text)

Original assignee

The original assignee is Brainguard Technologies Inc. According to the patent document, they filed the application on 2015-07-24 and were granted the patent on 2016-08-16. [cite: The full patent text] The patent describes protective gear, particularly helmets, designed to mitigate impact forces, rotational forces, and shear forces to prevent neurological damage. [cite: The full patent text] It is unclear from the provided text whether Brainguard Technologies Inc. shipped a product embodying the claims. The current status of Brainguard Technologies Inc. is "Active" [cite: The full patent text].

Assignment timeline

The USPTO Patent Assignment Search (https://assignmentcenter.uspto.gov/) shows no recorded assignments for US patent 9414635 after its issuance. The original assignment from the inventor to Brainguard Technologies Inc. would have occurred before or during the application filing process and is reflected in the "Original Assignee" field of the patent itself.

Timeline diagram

timeline
    title Ownership of US 9414635
    2011 : Priority date
    2015 : Application filed by Brainguard Technologies Inc
    2016 : Patent granted to Brainguard Technologies Inc

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The patent remains assigned to the original assignee, Brainguard Technologies Inc., and there is no record of transfer to a licensing-only LLC.

2. Known asserter in the chain — not present. Brainguard Technologies Inc. is not identified as a known NPE on the provided lists (Acacia Research Corp, Marathon Patent Group, Intellectual Ventures, IPNav, Wi-LAN, Mosaid/Conversant, Vringo, Pendrell, Innovatio IP Ventures, MPHJ Technology, Lumen View Technology, Round Rock Research, Document Generation Corp, Erich Spangenberg entities).

3. Repeat correspondent across the chain — not present. There is no chain of assignments to evaluate for a repeat correspondent.

4. Cascading transfers — not present. There are no recorded assignments to indicate cascading transfers.

5. Pre-litigation transfer — unclear. Without knowledge of any infringement suits, it is not possible to assess if a pre-litigation transfer occurred.

6. Bankruptcy fire-sale — not present. There is no information to suggest Brainguard Technologies Inc. has undergone bankruptcy proceedings and a subsequent patent sale.

7. Privateering — unclear. There is no public information in the patent document or search results to indicate a privateering arrangement.

8. Defensive aggregator (anti-NPE) — not present. The patent is not currently assigned to a known defensive aggregator like RPX, Allied Security Trust (AST), LOT Network, Unified Patents, or Open Invention Network (OIN).

Verdict

Insufficient data. There are no recorded assignments for US patent 9414635 after its issuance, meaning the patent is still owned by the original assignee, Brainguard Technologies Inc. Without any transfers, there is no assignment chain to analyze for NPE patterns.
Verification: https://assignmentcenter.uspto.gov/patent/index.html (search US9414635)

The user wants me to identify the most relevant prior art for US patent 9414635, provide full citations, publication/filing dates, brief descriptions, and potentially anticipated claims under 35 U.S.C. § 102.

I have already identified the independent claims of US9414635 and the key elements. I have also identified five highly relevant prior art patents from the citations list, including the four explicitly discussed in the '635 patent's "Description of Related Art" and one additional highly relevant WO application. I have verified that all these are prior art with priority dates preceding US9414635's priority date.

I will now compile the detailed analysis for each of these identified prior art documents.

Analysis of Prior Art for US9414635 "Biomechanics aware helmet"

The following prior art documents are identified as most relevant, based on their direct citation in US9414635 and their technical content addressing similar problems, particularly related to multi-layered helmet designs for impact and shear force attenuation.

1. U.S. Pat. No. 7,076,811 (Puchalski)

• Full Citation: US7076811B2, "Protective head covering having impact absorbing crumple or shear zone," issued to Puchalski Ione G on 2006-07-18.
• Publication/Filing Date: Priority Date: 2002-09-09; Publication Date: 2006-07-18.
• Brief Description: This patent describes a helmet featuring a shell composed of three or more discrete panels. These panels are designed to move relative to one another upon impact, creating a "crumple zone" or "shear zone" that dissipates and redirects impact forces away from the user's head. The movements can be initially recoverable, and with sufficient force, lead to permanent structural changes that absorb energy.
• Potential Anticipation (35 U.S.C. § 102): This patent directly anticipates key elements of US9414635, particularly the concept of relative movement between helmet components to absorb forces. It teaches an "outer shell layer" (the discrete panels) and a "shear mechanism allowing the outer shell layer to slide relative to the inner shell layer" (the panels moving relative to one another to create a shear zone). The structural changes and movement of the panels inherently involve an "absorptive/dissipative material" in a functional sense, as energy is dissipated through deformation and friction. This directly anticipates the core inventive concept of claims 1, 9, and 17 regarding a shear mechanism between layers allowing relative sliding for energy absorption, especially against shear forces.

2. U.S. Pat. No. 5,815,846 (Calonge)

• Full Citation: US5815846A, "Resistant helmet assembly," issued to Tecno-Fluidos, S.L. on 1998-10-06.
• Publication/Filing Date: Priority Date: 1996-11-27; Publication Date: 1998-10-06.
• Brief Description: This patent describes an impact-resistant helmet assembly that includes a first material layer and a second material layer with a gas chamber between them for impact dampening. Additionally, a containment layer over the second material layer defines a fluid chamber containing a viscous gel. This gel provides resistance against disbursement from an impacted region, enhancing impact distribution and dampening.
• Potential Anticipation (35 U.S.C. § 102): Calonge describes a multi-layered helmet with "a first material layer coupled to a second material layer" and uses a "viscous gel" as an "impact dampening" and "impact distribution" means. While it doesn't explicitly focus on "sliding" as the primary mechanism, the presence of a viscous gel between layers inherently allows for shear deformation and energy dissipation, which can be seen as a form of an "absorptive/dissipative material" within a shear mechanism. This could potentially anticipate the "first energy transformer having a first absorptive/dissipative material" of claims 1, 9, and 17, and more specifically claims 5, 6, 13, and 14 which specify the material as a gel or fluid.

3. U.S. Pat. No. 5,956,777 (Popovich)

• Full Citation: US5956777A, "Helmet," issued to Grand Slam Cards on 1999-09-28.
• Publication/Filing Date: Priority Date: 1998-07-22; Publication Date: 1999-09-28.
• Brief Description: This patent discloses a helmet designed to protect the head by laterally displacing impact forces. It comprises a rigid inner shell, a resilient spacing layer surrounding the inner shell, and an articulated outer shell. The articulated outer shell consists of multiple discrete rigid segments connected by resilient members, allowing for lateral displacement of impact forces.
• Potential Anticipation (35 U.S.C. § 102): Popovich's patent teaches a "rigid inner shell" and an "articulated shell having a plurality of discrete rigid segments" connected by "resilient members" and separated by a "resilient spacing layer." The stated function of "laterally displacing impact forces" suggests relative movement between the articulated outer shell and the inner components, which functions as a "shear mechanism." The "resilient spacing layer" and "resilient members" act as "absorptive/dissipative material." This could potentially anticipate the multi-layer structure, the shear mechanism allowing relative movement, and the energy absorption elements found in claims 1, 9, and 17.

4. U.S. Pat. No. 6,434,755 (Halstead)

• Full Citation: US6434755B1, "Helmet," issued to Southern Impact Research Center, Llc on 2002-08-20.
• Publication/Filing Date: Priority Date: 1999-06-04; Publication Date: 2002-08-20.
• Brief Description: This patent describes a football helmet featuring liner sections of varying thicknesses and densities. The design allows softer, thicker sections to absorb less intense impacts by crushing, while harder, thinner sections prevent bottoming out during more severe impacts.
• Potential Anticipation (35 U.S.C. § 102): While Halstead's patent details a layered cushioning system for impact absorption through compression, it does not explicitly disclose a "shear mechanism allowing the outer shell layer to slide relative to the inner shell layer" to address rotational forces as claimed in US9414635. Its primary focus is on managing linear impact forces and preventing bottoming out with different foam densities. Therefore, it is less likely to anticipate the specific sliding shear mechanism, though it is relevant to the general concept of multi-layer cushioning and absorptive materials. It may be broadly relevant to the "absorptive/dissipative material" aspect but not the claimed function of sliding for rotational force impact.

5. WO2012109381A1 (Innovation Dynamics LLC)

• Full Citation: WO2012109381A1, "Helmet omnidirectional energy management systems," published by Innovation Dynamics LLC on 2012-08-16.
• Publication/Filing Date: Priority Date: 2011-02-09; Publication Date: 2012-08-16.
• Brief Description: This international patent application describes helmets equipped with omnidirectional energy management systems. These systems typically incorporate multiple layers that are designed to move relative to one another to attenuate various impact forces, specifically highlighting their effectiveness in managing rotational forces through the use of low-friction layers to facilitate this relative movement.
• Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant and directly anticipates several key features of US9414635. It explicitly teaches "multiple layers designed to move relative to each other to attenuate forces, especially rotational forces." This directly corresponds to US9414635's claims of an "outer shell layer," an "inner shell layer connected to the outer shell layer through a shear mechanism allowing the outer shell layer to slide relative to the inner shell layer," and the objective of protecting against "rotational force impact while the outer shell layer is allowed to slide." The "low-friction layers" serve as the "first energy transformer having a first absorptive/dissipative material" that enables the sliding shear mechanism. Therefore, this patent application likely anticipates claims 1, 9, and 17, and potentially claims 2, 3, 10, 11, 18, and 19 which further define the shear mechanism as a shear layer and its connection through an energy transformer.

US Patent 9,414,635 (US'635) describes a biomechanics-aware helmet designed to mitigate not only direct impact forces but also rotational and shear forces, which are significant contributors to traumatic brain injury (TBI). The patent emphasizes that existing protective gear often fails to sufficiently dampen these rotational and shear forces, leading to neurological damage such as diffuse axonal injury (DAI) and coup-contrecoup injuries.

The core of the invention in US'635, as articulated in Claim 1, is a helmet featuring an outer shell layer and an inner shell layer. These layers are connected by a shear mechanism that allows the outer layer to slide relative to the inner layer. This shear mechanism includes a first energy transformer with an absorptive/dissipative material. A chin strap is attached to the inner shell layer to maintain its position on the wearer's head during rotational force impact, while the outer shell layer is allowed to slide.

A person having ordinary skill in the art (POSA) in helmet design, aware of the deficiencies of existing helmets in protecting against rotational and shear forces, as highlighted in US'635's own background, would have been motivated to combine prior art references to create a helmet with these improved protective qualities.

Obviousness Analysis under 35 U.S.C. § 103

The claims of US'635 would have been obvious to a POSA based on the combination of:

1. U.S. Pat. No. 7,076,811 (Puchalski)
2. U.S. Pat. No. 5,815,846 (Calonge)
3. General knowledge of helmet construction and components (e.g., chin straps, conforming liners).

Claim 1 Analysis

Claim 1: A helmet comprising: an outer shell layer; an inner shell layer connected to the outer shell layer through a shear mechanism allowing the outer shell layer to slide relative to the inner shell layer, wherein the shear mechanism includes a first energy transformer having a first absorptive/dissipative material, the inner shell layer configured to conform to a human head; a chin strap attached to the inner shell layer to maintain the position of the inner shell layer on the human head during rotational force impact while the outer shell layer is allowed to slide.

1. "A helmet comprising: an outer shell layer; an inner shell layer configured to conform to a human head; a chin strap attached to the inner shell layer..."

   • Helmets, outer shell layers, inner layers (or liners) configured to conform to a human head, and chin straps are fundamental and well-known components in the prior art for protective headgear. Puchalski and Calonge both disclose helmets. US'635 itself illustrates a conventional helmet (Helmet 201) with a shell layer 211, a lining layer 213 (configured to conform to a human head), and a chin strap 221. The patent further states that "Liners are provided beneath a hardened exterior shell to reduce violent deceleration of the head". The purpose of a chin strap is to secure the helmet, including its inner, head-conforming components, to the wearer's head.

2. "...connected to the outer shell layer through a shear mechanism allowing the outer shell layer to slide relative to the inner shell layer, wherein the shear mechanism includes a first energy transformer having a first absorptive/dissipative material..."

   • Puchalski discloses a helmet where the shell consists of "three (or more) discrete panels that are physically and firmly coupled together... but upon impact the panels move relative to one another... thereby permitting impact forces to be dissipated and/or redirected away from the cranium and brain within." This movement provides a "protective ‘crumple zone’ or ‘shear zone’". Puchalski thus teaches the critical concept of relative movement between helmet components (panels of a shell) to dissipate shear forces. A POSA, motivated by the need to address rotational and shear forces, would readily apply this principle to allow an outer shell layer to move relative to an inner shell layer.
   • Calonge describes an impact-resistant helmet assembly that includes "a fluid chamber in which a quantity of fluid is disposed. The fluid includes a generally viscous gel structured to provide some resistance against disbursement from an impacted region of the fluid chamber to non-impacted regions of the fluid chamber, thereby further enhance the impact distribution and dampening of the impact force provided by the helmet assembly". This clearly teaches the use of an "absorptive/dissipative material" (viscous gel) within a layer (fluid chamber) between helmet components for impact dampening and distribution. A viscous gel inherently allows for relative movement or "sliding" between the layers it separates, especially under shear forces, while dissipating energy.
   • Motivation to Combine: The motivation to combine Puchalski's concept of relative movement for shear dissipation with Calonge's use of a viscous gel as an absorptive/dissipative material is explicitly provided by US'635 itself. The patent identifies the "larger issue" as "preventing the tissue and neurological damage caused by rotational forces, shear forces, oscillations, and tension/compression forces" because "many pieces of protective gear do not sufficiently dampen, transform, dissipate, and/or distribute the rotational, tension, compression, and/or shear forces". A POSA, armed with this understanding, would be highly motivated to combine Puchalski's teaching of relative movement to create a "shear zone" with Calonge's viscous gel to effectively absorb and dissipate energy during such movement, thereby improving protection against rotational and shear forces. This combination directly results in a shear mechanism between helmet layers that allows sliding and incorporates an absorptive/dissipative material.

3. "...to maintain the position of the inner shell layer on the human head during rotational force impact while the outer shell layer is allowed to slide."

   • As noted, chin straps are conventional for securing a helmet to the wearer's head. When applied to a helmet designed with an inner layer that conforms to the head and an outer layer that slides, the chin strap's function remains unchanged: to keep the head-conforming inner layer in place. The phrase "while the outer shell layer is allowed to slide" merely describes the expected operational interaction of the combined components, not an inventive function of the chin strap itself.

Therefore, Claim 1 would have been obvious to a POSA motivated to improve helmet protection against rotational and shear forces by combining the teachings of Puchalski and Calonge with conventional helmet design elements.

Dependent Claims Analysis

• Claim 2 (shear mechanism is a shear layer): Calonge's fluid chamber containing viscous gel, acting as an impact dampening and distributing layer between material layers, inherently functions as a "shear layer". US'635 itself refers to "energy and impact transformer layers" that "flexibly connect the shell layers to absorb impact forces, rotational forces, shear forces, etc.". Making the shear mechanism a "shear layer" would be an obvious design choice for a POSA implementing such a system.
• Claim 3 (shear layer connected via first energy transformer with absorptive/dissipative material): This claim further defines the shear layer as the first energy transformer. As established, Calonge teaches a fluid chamber (layer) with viscous gel (absorptive/dissipative material) for dampening and distribution, which aligns directly with this structure.
• Claim 4 (second energy transformer): This claim introduces an additional energy transformer. US'635 explicitly describes and illustrates multiple shell systems (e.g., an outer, middle, and inner shell) with energy and impact transformative layers between them (FIG. 5 and FIG. 6) to address different types of forces. Puchalski also refers to "three (or more) discrete panels" in its shear zone. Given the objective of dissipating complex forces (rotational, shear, tension, compression), a POSA would find it obvious to add further layers of energy-absorbing material, similar to Calonge's gel or the other materials mentioned in US'635, to further enhance protection and dissipate residual forces.
• Claim 5 (gel as absorptive/dissipative material): Directly taught by Calonge, which uses a "viscous gel" for impact dampening. US'635 also lists "gels" as a material for its energy and impact transformer layers.
• Claim 6 (fluid as absorptive/dissipative material): Directly taught by Calonge, which uses a "fluid chamber". US'635 also lists "fluids" as a material for its energy and impact transformer layers.
• Claim 7 (electro-rheological element as absorptive/dissipative material): US'635 itself states that the "outer and inner energy and impact transformer layers may be constructed using gels, fluids, electro-rheological elements, magneto-rheological elements, etc.". It further details how electro-rheological elements, as "smart fluids," have electric field-dependent viscosity and can "react within milliseconds to reduce impact and shear forces between shells". Given Calonge's teaching of a viscous fluid, substituting it with a known "smart fluid" like an electro-rheological element for enhanced, active control of viscosity in response to impact would be an obvious improvement for a POSA.
• Claim 8 (lining layer connected to inner shell layer): A lining layer in a helmet for comfort, fit, and additional energy absorption is a standard, conventional feature. US'635's description of a conventional helmet (FIG. 2) includes a "lining layer 213" connected to the shell layer 211, noting it "may include lining materials, foam, and/or padding to absorb mechanical energy and enhance fit".

Claims 9-20, which relate to "Protective gear" or a "helmet" and use an "inner conforming layer" instead of an "inner shell layer," are similarly obvious for the reasons stated above. An "inner conforming layer" is functionally equivalent to an "inner shell layer configured to conform to a human head" and can be implemented by a lining, foam, or padding, as described in US'635 itself.

In conclusion, a POSA, motivated to improve helmet protection against the recognized problem of rotational and shear forces, would find it obvious to combine the shear-mitigating relative movement taught by Puchalski with the energy-absorbing viscous gel taught by Calonge, integrated into a conventional helmet structure with standard features like a chin strap and conforming inner layers. The dependent claims merely elaborate on these obvious design choices and material selections.