Patent Publication Number: US-2023148699-A1

Title: Adjustable helmet assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 17/067,013, entitled “Adjustable Helmet Assembly,” filed Oct. 9, 2020, which is a continuation of Patent Cooperation Treaty Application Serial No. PCT/US2019/027557, entitled “Adjustable Helmet Assembly,” filed Apr. 15, 2019 which claims benefit of U.S. Provisional Patent Appl. Ser. No. 62/657,744 entitled “Collapsible Helmet Impact Zones,” filed Apr. 14, 2018, U.S. Provisional Patent Appl. Ser. No. 62/716,066 entitled “No Tool Adjustable Helmet System,” filed Aug. 8, 2018 and U.S. Provisional Patent Appl. Ser. No. 62/792,573 entitled “No Tool Adjustable Helmet System, filed Jan. 15, 2019, which all disclosures are incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an adjustable helmet system assembly and a method for fitting the adjustable helmet system assembly to a wearer&#39;s head. The adjustable helmet system assembly includes a locking mechanism that allows the front shell to be movable or slidable to a rear shell to adjust to a desired length. Furthermore, the adjustable helmet system assembly may incorporate crumple zones or crumple features that allow the adjustable helmet system assembly to undergo structural changes in a pre-determined fashion so that the structural changes are recoverable but yet provide protection. 
     BACKGROUND OF THE INVENTION 
     Adjustable helmets have been known in the art for years, and used in different applications such as sports, firefighting, construction work, and the military. In particular, many of these adjustable helmets allow the wearer to adjust the helmet size to fit a particular head. For example, helmet adjustment mechanisms have consisted of a stud and notch or a headband with a rack and pinion adjusting mechanism, and/or by loosening and tightening screws. 
     Although, these and other conventional adjustment mechanisms have worked well, they have failed in a number of areas. For instance, loosening and tightening screws increase the length of adjustment time, require that the user carries tools and do not allow the helmet wearer to adjust the size of the helmet while wearing the helmet and/or adjust the helmet quickly. Accordingly, the helmet wearer must remove the helmet, adjust the helmet, and retry the helmet size multiple times before a proper fit can be established. 
     Also, in many other adjustable helmet designs, the adjustment does not allow the comfort liner padding to be properly fitted to the head of the user. Comfort liner padding assemblies are usually provided in standard sizes (e.g., small to xlarge) and are affixed to the helmet. The comfort liner padding assemblies are not adjustable, these variances create significant difficulties in having the helmet sized correctly with the comfort liner pad system. The comfort liner pad system may be improperly positioned, too large or too small preventing or decreasing the safety of its intended function. 
     Furthermore, the previous adjustable helmet designs are usually manufactured from rigid or substantially rigid polymers. These rigid polymers do not perform as intended because they lack the ability absorb a significant amount of energy after an impact and/or manufacturers tend to increase the relative thickness of the material. Using such materials or increased thicknesses, allows the impact force to be transferred to the wearer&#39;s head, thus causing severe traumatic brain injuries or result in adding unnecessary weight/imbalance resulting in disproportionate measurements for optimal muscle control. Accordingly, the impact force can also be transferred to other portions of the helmet, potentially causing premature disengagement of the helmet shells and exposing the wearer to further traumatic brain injuries. 
     BRIEF SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an adjustable helmet system with improved locking mechanisms and crumple zones that can overcome some of the disadvantages of the previous helmet designs. The adjustable helmet system offers a two-piece helmet that allows adjustment of the helmet quickly and efficiently without the need for tools, allow the impact mitigation layers and/or comfort liners pad systems to be easily disconnected and/or adjusted within the helmet, and/or provide for controlled localized deflection and/or deformation through the incorporation of structural features that promote the absorption of energy from an impact resulting in reduced forces experienced by the wearer and other portions of the helmet. 
     Another practical advantage with this adjustable helmet system that also improves safety by enabling a better customizing to fit different head shapes such as oval, oblong and round, not just adapt to sizes. Parents will be able to customize the helmets as their children grow, thus avoiding the understandable but dangerous habit of buying large so that the child will ‘grow into it’. A frontal fall in a helmet that is too large, forces the helmet backwards and can force the back of the helmet into the neck at the base of the skull, at the anatomical area of the brain stem, with tragic results often worse than if a helmet had not been worn at all. 
     In one embodiment, the adjustable helmet system may comprise a locking system. The adjustable helmet system comprises a first (or front) shell; a second (or back) shell, the second shell being slidably attached to the first shell; a locking mechanism, the locking mechanism being movable between a first unlocked position which allows the first and second shells to slide relative to each other and a second locked position which inhibits the first and second shells from sliding relative to each other. 
     In one embodiment, an adjustable helmet system may comprise a helmet clamp locking mechanism assembly. The adjustable helmet system may comprise a front shell, a back shell, and a clamp locking assembly. The clamp locking assembly will facilitate easy no-tool detachment and securement by using a lever function. To adjust a representative helmet, the user may lift the clamp body allowing the clamp post to place a downward compressive force against the clamp tongue thereby releasing the front and back shells to move relative to each other. Conversely, to secure or lock the clamp locking assembly, the user will push the clamp body down within the cavity allowing the base plate coupled to the clamp post to place an upward compressive force to sandwich the front and back shells and prevent movement and have the plurality of teeth engage with the plurality of recesses. Alternatively, the helmet may further comprise helmet alignment guides. The helmet alignment guides may be strategically placed onto the helmet and can be placed within any region of the helmet, including frontal, ridge (or top), and/or the sides (right or left). The helmet alignment guides will help align the front and back shells in the proper position during adjustment. 
     In one embodiment, the adjustable helmet system may comprise a clamp locking mechanism assembly that may be modular and coupled to any commercially available helmet (retrofitting a commercially available helmet). The clamp locking mechanism assembly may comprise at least one of a clamp housing, a clamp body, clamp post, a base plate, a clamp tongue and/or any combination thereof. The clamp housing has a top surface and a bottom surface, at least a portion of the top surface having a cavity extending from the top surface towards the bottom surface, the cavity sized and configured to receive the clamp body, the cavity having an aperture, the aperture extends through the top surface to the bottom surface, the aperture is sized and configured to receive a clamp post, the clamp post is pivotally coupled to the clamp body; the clamp housing bottom surface having a plurality of teeth, the plurality of teeth extending outwardly from the bottom surface, the plurality of teeth sized and configured to fit within a plurality of recesses on a clamp tongue. The clamp tongue having a first surface and a second surface, at least a portion of the first surface including the plurality recesses, the plurality of recesses sized and configured to receive the clamp housing plurality of teeth, the clamp tongue having a channel, the channel extends through the first surface to the second surface, the channel sized and configured to receive the clamp post; the clamp post coupled to a base plate. 
     In another embodiment, the adjustable helmet system may comprise a clamp locking mechanism that may be integrated within a helmet. The adjustable helmet system comprises a helmet and a clamp locking mechanism assembly. The clamp locking mechanism assembly may comprise at least one of a clamp housing, a clamp body, clamp post, a base plate, a clamp tongue, a spring and/or any combination thereof. The helmet having a front shell, and a back shell, at least a portion of the front or back shell having one or more alignment guides; the front or back shell may have a clamp tongue, the clamp tongue having a longitudinal length that extends outward from the front or back shell, the clamp tongue having a first surface and a second surface, at least a portion of the first surface including a plurality recesses, the plurality of recesses sized and configured to receive a plurality of teeth, the clamp tongue having a channel, the channel extends through the first surface to the second surface, the channel sized and configured to receive the clamp post; the clamp post coupled to the base plate; at least a portion of the back or front shell having first surface and a second surface, the front or back shell first surface having a shell recess, the shell recess being sized and configured to fit a clamp housing, the shell recess having an shell aperture extends there through, the shell aperture being sized and configured to receive the clamp post; at least a portion of the front or back shell second surface having a plurality of teeth, the plurality of teeth sized and configured to fit within the plurality of recesses. The clamp housing has a top surface and a bottom surface, at least a portion of the top surface having a cavity extending from the top surface towards the bottom surface, the cavity sized and configured to receive the clamp body, the cavity having an aperture, the aperture extends through the top surface to the bottom surface, the aperture is sized and configured to receive a clamp post, the clamp post is pivotally coupled to the clamp body. 
     In another embodiment, the adjustable helmet system may comprise an alternate embodiment of a clamp locking mechanism that may be integrated within a helmet. The adjustable helmet system may comprise a front shell (or first shell), and back shell (or second shell), and a locking mechanism. The locking mechanism including a clamp assembly, a plurality of teeth, at least a portion of the plurality of teeth sized and configured to fit within a portion of a plurality of recesses, the plurality of teeth disposed on the first or second shell, a plurality recesses, at least a portion of the plurality of recesses are sized and configured to receive the plurality of teeth, the plurality of recesses disposed on the first or second shell, the clamp assembly being movable between a unlocked position that allows the plurality of teeth and the plurality of recesses to disengage and allow the first and second shells to slide relative to each other, and a locked position that allows a portion of the plurality of teeth and a portion of the plurality of recesses to engage that inhibits the first and second shells from sliding relative to each other. 
     In another embodiment, the adjustable helmet system may comprise crumple zones. The adjustable helmet system may comprise a first shell, a second shell, the second shell being slidably attached to the first shell, a locking mechanism, and/or at least one opening. The locking mechanism being movable between an unlocked position which allows the first and second shells to slide relative to each other and a locked position which prohibits the first and second shells from sliding relative to each other. The at least one opening placed adjacent to, in proximity to or within impact zones of the first or second shells resulting in local deformation and reducing the translation of impact forces from a portion of the first shell and/or second shells. The impact zones are zones of a wearer&#39;s head that may see higher than normal frequency of impacts and/or magnitude of impacts. The impact zones are within the occipital region, temporal region, parietal region, orbit region, the frontal region, the mandible (front, right and/or left side) region, the maxilla region, the nasal region, zygomatic region, the ethmoid region, the lacrimal region, the sphenoid region and/or any combination thereof 
     In another embodiment, the adjustable helmet system may further comprise at least one impact mitigation layer. The adjustable helmet system may comprise a front shell (or first shell), a back shell (or second shell), a locking mechanism, and at least one impact mitigation layer. The at least one impact mitigation layer may include one or more impact structures. The impact structures may comprise at least a portion of liner pod assemblies, at least a portion of filaments, at least a portion of laterally supported filaments (LSFs), at least a portion of auxetic structures, TPU (not shown), inflatable bladders (not shown), shock bonnets (not shown), at least one foam layer (not shown), at least a portion of air bladders, and/or any combination thereof The front shell and/or back shell may have an external surface and an internal surface, the at least one impact mitigation layer may be coupled to the internal surface of the front and/or back shells. Coupling may be fixed or removably coupled. 
     In another embodiment, the adjustable helmet system may further comprise at least one supplemental layer. The adjustable helmet system may comprise a front shell (or first shell), a back shell (or second shell), a locking mechanism, at least one impact mitigation layer and at least one supplemental layer. The front shell and/or back shells may have an external surface and an internal surface, the supplemental layer may be positioned proximate to the impact mitigation layer and/or may be positioned proximate to the internal surface of the front and/or back shells. The supplemental layer may include a plurality of liner pod assemblies or comfort liners that are desirably positioned around various locations of the wearer&#39;s head, covering much of the area inner surface of the helmet. The liner pod assemblies may include a pod and a connection mechanism. Such plurality of liner pod assemblies may be positioned within and/or proximate to one or more of the following regions: a frontal assembly (or front), an occipital assembly (or lower-back), a mid-back assembly, a parietal assembly (or midline), and a temporal assembly (right and/or left sides), and/or any combination(s) thereof. At least a portion of the liner pod assemblies may be removably coupled to the helmet and/or any combination thereof to increase energy absorption, mitigation of linear or angular impact forces, enhance fit and comfort. 
     In another embodiment, the adjustable helmet system may comprise a cam locking mechanism assembly. The cam locking assembly will facilitate easy no-tool detachment and securement by using a rotational function. To adjust a representative helmet, the user may rotate the cam body counter-clock position to allowing the cam post to place a downward compressive force against the clamp tongue thereby releasing the front and back shells to move relative to each other. Conversely, to secure or lock the cam locking assembly, the user will rotate the cam body to a clock-wise position to lift the base plate that coupled to the clamp post and place an upward compressive force to sandwich the front and back shells and prevent movement and have the plurality of teeth engage with the plurality of recesses. Alternatively, the helmet may further comprise helmet alignment guides. The helmet alignment guides may be strategically placed onto the helmet and can be placed within any region of the helmet, including frontal, ridge (or top), and/or the sides (right or left). The helmet alignment guides will help align the front and back shells in the proper position during adjustment. 
     In one exemplary embodiment, at least one commercially available (CA) may be retrofitted to have one or more crumple zones. The at least one CA helmet may comprise one or more protrusions that may be modified or replaced with impact mitigation structures or impact mitigation features to create a crumple zone. The one or more protrusion may be modified with impact mitigation features that allow the collapsibility, compressibility and/or impact absorption, the impact mitigation features comprising a plurality of perforations, the plurality of perforations may include a variety of different shapes and/or configurations to enhance collapsibility, compressibility and/or impact absorption. Such shapes and/or configurations may include relief cuts, slits, holes, openings, herringbone shape, zig-zag shapes, chevron shapes, auxetic shapes, reentrant shapes, and/or any combination thereof In another exemplary embodiment, the one or more protrusion may incorporate at least one impact mitigation structure over the shell protrusions. Additionally, the one or more shell protrusions may be replaced with at least one impact mitigation structure. The at least one CA helmet shell protrusions may have at least one impact mitigation structure disposed within a cavity of the one or more protrusions. Alternatively, the at least one impact mitigation structure can be positioned between the at least two protrusions. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIGS.  1 A- 1 F  depicts various views of one embodiment of an adjustable helmet assembly; 
         FIG.  1 G  depicts an exploded view of one embodiment of an adjustable helmet assembly of  FIGS.  1 A- 1 F ; 
         FIGS.  2 A- 2 J  depict various views of an alternate embodiment of an adjustable helmet assembly; 
         FIGS.  3 A- 3 F  depict various views of one embodiment of an adjustable helmet first or front shell; 
         FIGS.  4 A- 4 F  depict various views of one embodiment of an adjustable helmet second or back shell; 
         FIGS.  5 A- 5 G  depict various views of an alternate embodiment of an adjustable helmet; 
         FIGS.  6 A- 6 H  depict various views of an alternate embodiment of a clamp locking mechanism assembly; 
         FIGS.  6 I- 6 J  depict an exploded isometric and side view of one embodiment of a clamp locking mechanism assembly of  FIGS.  6 A- 6 H ; 
         FIGS.  7 A- 7 H  depict various views of one embodiment of the clamp housing; 
         FIGS.  8 A- 8 H  depict various views of one embodiment of a clamp body; 
         FIGS.  9 A- 9 G  depict various views of one embodiment of a clamp post; 
         FIGS.  10 A- 10 H  depict various views of one embodiment of a clamp tongue; 
         FIGS.  11 A- 11 H  depict various views of one embodiment of a cam locking mechanism assembly; 
         FIGS.  11 I- 11 J  depict various exploded views of the cam locking mechanism assembly of  FIGS.  11 A- 11 H ; 
         FIGS.  12 A- 12 H  depict various views of one embodiment of a cam tongue; 
         FIGS.  13 A- 13 H  depict various views of one embodiment of the cam housing; 
         FIGS.  14 A- 14 H  depict various views of one embodiment of a cam post; 
         FIGS.  15 A- 15 H  depict various views of one embodiment of a cam body; 
         FIGS.  16 A- 16 F  depict various views of an alternate embodiment of a clamp body; 
         FIGS.  17 A- 17 D  depict various views and magnified views of a method to open and close a clamp locking assembly; 
         FIGS.  18 A- 18 D  depict various magnified views of a method to open and close a clamp locking assembly with engagement features; 
         FIGS.  19 A- 19 E  depict various views of one embodiment of an ear protection; 
         FIGS.  20 A- 20 I  depict various views of different embodiments of crumple zones on an adjustable helmet; 
         FIGS.  21 A- 21 F  depict various views of different embodiments of commercially available helmets without crumple zones and locations of the at least one shell protrusions; 
         FIGS.  22 A- 22 B  illustrate an alternate embodiment of a commercially available (CA) helmet without crumple zones; 
         FIG.  23    depict one embodiment of a CA helmet with at least one impact mitigation feature; 
         FIGS.  24 A- 24 F  depict various embodiments of impact mitigation features shape and configurations; 
         FIG.  25    depicts one embodiment of a CA helmet having impact mitigation structure over a shell protrusion; 
         FIGS.  26 A- 26 B  depicts one embodiment of a CA helmet having an impact mitigation structure replacing the shell protrusion; 
         FIG.  27    depicts one embodiment of a CA helmet having an impact mitigation structure disposed within the shell protrusion; 
         FIGS.  28 A- 28 D  depict one embodiment of an impact mitigation structure comprising filaments; 
         FIGS.  29 A- 29 C  depict one embodiment of an impact mitigation structure comprising laterally supported filaments; 
         FIGS.  30 A- 30 C  depict one embodiment of an impact mitigation structure comprising an array of laterally supported filaments on a flexible layer; 
         FIGS.  31 A- 31 B  depict one embodiment of an impact mitigation structure comprising auxetic structures; 
         FIG.  32 A- 32 C  depict various embodiments of at least one impact mitigation pads; 
         FIGS.  33 A- 33 D  depict various views of one embodiment of one or more liner pod assemblies; 
         FIGS.  34 A- 34 B  depict various bottom isometric views of an alternate embodiment of one or more liner pod assemblies; 
         FIGS.  35 A- 35 D  depict various views of one embodiment of a liner pod assembly; 
         FIGS.  36 A- 36 C  depict various views of one embodiment of a connection mechanism for a liner pod assembly. 
         FIGS.  37 A- 37 B  depicts a side view of one embodiment of a separate sliding structure; 
         FIGS.  38 A- 38 G  depict various view of an alternate embodiment of an adjustable helmet; 
         FIGS.  38 H- 38 I  depict a cross-sectional view and an exploded cross-sectional view of the alternate embodiment of the adjustable helmet of  FIGS.  38 A- 38 G ; 
         FIGS.  39 A- 39 H  depict various views of an alternate embodiment of an adjustable helmet first or front shell; 
         FIGS.  40 A- 40 G  depict various views of an alternate embodiment of an adjustable helmet second or back shell; 
         FIGS.  41 A- 41 G  depict various views of an alternate embodiment of a clamp body; 
         FIGS.  42 A- 42 H  depict various views of an alternate embodiment of a clamp post; 
         FIGS.  43 A- 43 F  depict various views of an alternate embodiment of an ear protection; 
         FIGS.  44 A- 44 F  depict various views of one embodiment of an ear loop. 
         FIG.  45    depicts a cross-sectional front view of the helmet and impact mitigation layer; 
         FIGS.  46 A- 46 B  depict a side and cross-sectional view of one embodiment of a supplemental layer; and 
         FIGS.  47 A- 47 C  depict various views of one embodiment of a ridge or crown foam pad. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The various improved locking mechanisms provided herein are depicted with respect to hockey, but it should be understood that the various devices and systems may be suitable for use in protecting players in various other athletic sports, as well as law enforcement, military and/or informal training session uses. For example, the embodiments of the present invention may be suitable for use by individuals engaged in athletic activities such as baseball, bowling, boxing, cricket, cycling, motorcycling, golf, hockey, lacrosse, soccer, rowing, rugby, running, skating, skateboarding, skiing, snowboarding, surfing, swimming, table tennis, tennis, or volleyball, or during training sessions related thereto. 
     Accordingly, the adjustable helmet system with improved locking mechanisms provide significant benefits that can overcome some of the disadvantages of the previous adjustable helmet designs. The adjustable helmet system offers a two-piece shelled helmet that allows adjustment and/or locking of the helmet quickly and efficiently without the need for tools, it allows the locking and/or unlocking of the helmet with one handed function, it can allow for the impact mitigation layers and/or comfort liners pad systems to be easily disconnected and/or adjusted within the helmet, and/or provide for localized deflection through the incorporation of structural features that promote the absorption of energy from the impact in more predictable ways. The adjustability is key should the players or wearers decide to improve their impact protection during play, and exchange at least a portion of the impact mitigation layer and/or at least a portion of the supplemental layer based on the frequency or severity of impact. Then, the adjustable helmet system may be properly adjusted to accommodate the comfort and sizing of the specific wearer. 
     Adjustable Helmet Assembly 
       FIGS.  1 A- 1 F  depicts various views of one embodiment of an adjustable helmet assembly  101 .  FIG.  1 G  depicts an exploded isometric view of the adjustable helmet assembly  101 . The adjustable helmet assembly  101  comprises an adjustable helmet system  102 , and an impact mitigation layer  103 . The adjustable helmet assembly may further comprise at least one inner shell  104 , a supplemental layer  105 , an ear protection  106 , an ear loop  107 , a visor  108 , a chinstrap (not shown) and/or any combination thereof 
     In one exemplary embodiment, the adjustable helmet assembly  101  comprises an adjustable helmet system  102 , an impact mitigation layer  103 , an inner shell  104 . The adjustable helmet assembly  101  may further comprise a supplemental layer  105 . The impact mitigation layer  103  nests within the adjustable helmet system  102 , and the impact mitigation layer  103  disposed between the adjustable helmet system  102  and the inner shell  104 . The supplemental layer  105  nests within the inner shell  104 , where an exterior surface of the supplemental layer  105  is adjacent to an interior surface of the inner shell  104 . 
     Adjustable Helmet System 
       FIGS.  2 A- 2 J  depict various views of different embodiments of an adjustable helmet system  201 . In one embodiment, the adjustable helmet system  201  may comprise a front shell (or first shell)  206 , a back shell (or second shell)  202  and a locking mechanism  208 . The locking mechanism may comprise a clamp lock mechanism and/or a cam lock mechanism. The locking mechanism  208  further comprising a clamp tongue  214 , a clamp body  213  and a clamp recess  215 . The first  206  and/or second shell  202  may be slidably connected, slidably coupled and/or rotatably coupled together via the locking and unlocking of the locking mechanism  208 . More specifically, the locking mechanism  208  being movable between an unlocked position which allows the first  206  and second shells  202  to slide relative to each other and a locked position which prohibits the first  206  and second shells  202  from sliding relative to each other. The adjustable helmet system  201  may further comprise additional features, including helmet alignment guides  203 , a side plate  204 , ear protection  204 , a front plate  207 , a center plate  209 , one or more openings  210 , one or more crumple zones  211 , one or more securement holes  212  and/or any combination thereof. 
     The locking mechanism  208  may be a modular assembly and/or integrated within the first  206  and/or second  202  shells. In one embodiment, the locking mechanism comprises a clamp assembly, a plurality of teeth, at least a portion of the plurality of teeth sized and configured to fit within a portion of a plurality of recesses, the plurality of teeth disposed on the first or second shell, a plurality of recesses, at least a portion of the plurality of recesses are sized and configured to receive the plurality of teeth, the plurality of recesses disposed on the first or second shell, the clamp assembly being movable between an unlocked position that allows the plurality of teeth and the plurality of recesses to disengage and allows the first and second shells to slide relative to each other, and a locked position that allows the a portion of the plurality of teeth and a portion of the plurality of recesses to engage and inhibits the first and second shells from sliding relative to each other. 
     The first  206  and/or second shell  202  may be manufactured from a relatively rigid material, such as polyethylene, nylon, polycarbonate materials, acrylonitrile Butadiene Styrene (ABS), polyester resin with fiberglass, thermosetting plastics, and/or any other rigid thermoplastic materials. Alternately, the first and/or second shell may be manufactured from a relatively deformable material, such as polyurethane and/or high-density polyethylene, where such material allows local deformation upon impact.  FIGS.  5 A- 5 G  and  FIGS.  38 A- 38 I  depict various views of an alternate embodiments of an adjustable helmet. 
       FIGS.  3 A- 3 F  depict various views of one embodiment of a first shell or front shell  301 . The first shell  301  may comprise a top portion  303 , a front portion  302 , and/or side portions  304  (e.g., right and left sides). The front portion  302  is positioned within the frontal region of a wearer&#39;s head and may extend towards the rear or back of the wearer&#39;s head, covering at least portions of top portion  303  or the crown region and/or the right and left temporal regions of the wearer&#39;s head or the side portions  304 , where the edge is at or immediately adjacent to the wearer&#39;s eyebrows. The front portion  302  may comprise a front plate  307  and securement holes  306  to secure the front plate  307  to the front portion  302 . The front plate  307  may be utilized as aesthetic feature and/or a logo may be disposed onto the front plate. Alternatively, the front plate  307  may comprise at least a portion of an impact mitigation structure as disclosed herein. The impact mitigation structure may be affixed to the first shell  301  and the front plate  307  may be affixed to the impact mitigation structure and/or the first shell  301 . The front plate  307  may have securement holes  306  and/or other features to affix the front plate  307  to the first shell  301 . The securement holes  306  and/or features may comprise rivets, screws, snaps, Velcro, adhesive, press fit, and/or any combination thereof The first shell  301  may further comprise a plurality of openings  305 , where the openings may provide for ventilation and/or give rise to one or more crumple zones  310 . The one or more openings  305 , the one or more openings  305  being elongated and having a width and a length, the length being at least two times larger than the width. The one or more openings  305  may comprise one or more tabs (not shown) that span the width of the one or more openings  305 .  FIGS.  39 A- 39 H  depict various views of an alternate embodiment of a first or front shell. 
     The top portion  303  of the first or front shell  301  may be positioned on a portion of a central ridge of a wearer&#39;s head and covering a portion of the parietal region of a wearers head as shown as  FIG.  3 C- 3 D . The top portion  303  of the first or front shell  301  may comprise a central plate  308 , one or more openings  305  and a portion of the lock mechanism, the central plate  308  having a perimeter edge  311 , the perimeter edge  311  sits below the perimeter edge  312  of the top portion  303 , leaving an indentation or recessed area disposed within the top portion  303 . The top portion  303  may further comprise one or more openings  305 , the one or more openings  305  being elongated and having a width and a length, the length being at least two times larger than the width. The one or more openings  305  may further comprise one or more tabs (not shown) that spans the width of the one or more openings  305 . Additionally, the central plate  308  includes a clamp tongue  313 . The clamp tongue  313  may be positioned adjacent or proximate to the central plate  308  of the first or front shell. The clamp tongue  313  being a longitudinal member having a first end and a second end, the first end affixed to the central plate  308 , and the second end extending away from the central plate  308  of the top portion  303  of the first or front shell  301  on a substantially similar planar surface or on the same plane as the central plate  308 . Substantially similar may include an offset plane having a range of minus 20 to plus 20 degrees difference (or a 0.25 in to 2 in below the planar surface of the central plate  308 ) from the co-planar surface of the top portion  303  and/or the co-planar surface of the central plate  308  of the first or front shell  301 . The clamp tongue  313  having a top surface  317 , a bottom surface  316  and a first channel  314 . The clamp tongue top surface  317  having a plurality of a plurality recesses  315  disposed onto the top surface  317 , at least a portion of the plurality of recesses  315  are sized and configured to receive a portion of a plurality of teeth  413  (see  FIG.  4 D ) and/or are sized and configured to engage a portion of a plurality of teeth  413 , the first channel  314  sized and configured to receive a clamp post  420  (see  FIG.  4 F ).  FIGS.  39 E- 39 F  depict various views of an alternate embodiment of a top portion of a first or front shell. 
     The side portions  304  of the first or front shell  301  may be positioned within or near the temporal regions of the wearer, covering the right and left sides of the wearer and/or at least a portion of the wearer&#39;s mandible as shown in  FIG.  3 E- 3 F . The side portions  304  may comprise at least one side plate (not shown), at least one side plate recess  318 , one or more securement holes  306 , one or more openings  305  and/or any combination thereof The side plate being disposed within the side plate recess  318 , and the securement holes  306  secure the side plate within the side plate recess  318 . The side portion  304  may further comprise or more openings  305 , the one or more openings  305  being elongated and having a width and a length, the length being at least two times larger than the width. The top portion  303  may further comprise one or more tabs (not shown) that couple the central plate  308  to the top portion  303 . The one or more tabs (not shown) may span the width of the one or more openings  318 . The first shell side portions  304  may further comprise an ear cover. The ear cover may comprise a portion of the shell that extends proximate to the wearer&#39;s ear for protection. The ear cover may include holes for further securement of a chin strap (not shown). In another embodiment, the first shell side portion may further comprise a side plate recess  318  and/or a side plate (not shown). The side plate recess  318  may be disposed on a portion of the first shell side portion  304 , the side plate recess  318  may be sized and configured to receive the side plate. The side plate may be sized and configured to fit within the side plate recess  318 . Alternatively, the side plate may be affixed to a portion of the first shell side portion  304 . The side plate may be utilized as aesthetic feature and/or a logo may be disposed onto the side plate. Alternatively, the side plate may comprise at least a portion of an impact mitigation structure as disclosed herein, the impact structure may be disposed within the side plate recess  318 , and the side plate positioned over the impact structure. The side plate may have securement features to affix the side plate to the first shell  301 . The securement features may comprise rivets, screws, snaps, Velcro, adhesive, press fit and/or any combination thereof.  FIGS.  39 G- 39 H  depict various views of an alternate embodiment of a side portion of a first or front shell. 
       FIG.  3 F  depicts a cross-sectional view of one embodiment of a side portion  304  of the first shell  301 . The first shell  301  may further comprise one or more alignment protrusions  319  that longitudinally extends perpendicular or substantially perpendicular from an interior or exterior surface of the side portion  304 . Such one or more alignment protrusions  319  may be sized and configured to fit within one or more alignment protrusion channels  403 . The alignment protrusions  319  are inserted within the one or more alignment protrusion channels  403  (see  FIG.  4 E ) to allow the first shell  301  and the back shell  401  to mate and facilitate the proper alignment to slidably connect at a fixed distance. The one or more alignment protrusions  319  may be molded directly onto the first shell  301  and/or the one or more alignment protrusions  319  may be affixed by a separate structure. The separate structure may comprise a base, and the one or more protrusions perpendicularly extending upwards from the base, the base being coupled to the first shell  301 . The slidable fixed distance may range from 1 mm to 40 mm. The alignment protrusion channels  403  having a width and length, the length of the alignment protrusion channel  403  being a range from 1 mm to 40 mm. The first shell  301  side portion  304  may further comprise a plurality of openings  305 , where the openings may provide for ventilation and/or give rise to one or more crumple zones. The one or more openings  305  being elongated and having a width and a length, the length being at least two times larger than the width. The side portion  304  may further comprise one or more tabs (not shown), the one or more tabs (not shown) may span the width of the one or more openings  305 .  FIG.  39 H  depicts a cross-sectional view of an alternate embodiment of a side portion of the first shell. 
       FIGS.  4 A- 4 F  depict various views of one embodiment of a second shell, back shell or rear shell  401 . The second shell  401  may comprise a back portion  408 , a top portion  411  and/or a side portion  419 . In one embodiment, the second shell  401  may comprise a portion of the lock mechanism  404 , one or more openings  402  giving rise to one or more crumple zones  407 , a central plate  406 , and one or more alignment protrusion channels  403 , and/or any combination thereof. More specifically,  FIG.  4 B  illustrates a back view of one embodiment of a back portion  408  of the second or back shell  401 . The back portion  408  may of the second or back shell  401  may comprise a central plate  406 , the central plate  406  having a perimeter edge  409 , the perimeter edge  409  sits below the perimeter edge  410  of the back portion  408  of the second or back shell  401 , leaving an indentation, depressed or recessed area disposed within the back portion  408  of the second or back shell  401 . The central plate  406  may extend from the lower occipital region (or lower back) up towards the mid-back region and to the top portion  411  of the second or back shell  401 . The back portion  408  may further comprise one or more tabs  405  that couple the central plate  406  to the back portion  408  of the second or back shell  401 .  FIGS.  40 A- 40 G  depict various views of an alternate embodiment of a second or back shell, and specifically,  FIGS.  40 C- 40 D  depict a front and back view of an alternate embodiment of a back portion of a second or back shell. 
       FIGS.  4 C- 4 D  illustrate the top and bottom view of one embodiment of a top portion  411  of the second or back shell  401 . The top portion  411  of the second or back shell  401  covering at least a portion of the crown region of the head and extends towards a portion the back portion that covers the occipital and/or the temporal region of the head. The top portion  411  of the second or back shell  401  may comprise a central plate  406  and a portion of the lock mechanism  404 , the central plate  406  having a perimeter edge  409 , the perimeter edge  409  sits below the perimeter edge  410  of the top portion  411 , leaving an indentation or recessed area disposed within the top portion  411  of the second or back shell  401 . The top portion  411  may further comprise one or more tabs  412  that couple the central plate  406  to the top portion  411  of the second or back shell  401 . Additionally, the central plate  406  includes a portion of a lock mechanism  404 , the lock mechanism comprising a plurality of teeth  414 . The central plate  406  may further comprise a central plate external surface  417  and a central plate internal surface  418 , the central plate external surface  417  having a recess  413 , the recess extending from the central plate external surface  417  towards the central plate internal surface  418 . The recess  413  further comprising a recess external surface  412  and a recess internal surface  415 . The recess internal surface  415  comprising a plurality of teeth  414 , the plurality of teeth  414  perpendicularly extending away from the recess internal surface  415 . The plurality of teeth  414  having different cross-sectional shapes and configurations, the shapes and configurations of the plurality of teeth  414  to be sized to fit within a portion of the plurality of recesses  315  of the clamp tongue  313 .  FIGS.  40 C- 40 D  depict a top and bottom view an alternate embodiment of a top portion of a second or back shell. 
     Furthermore, the recess external surface  415  of the top portion  411  of the second or back shell  401  may further comprise a clamp post  420 . The clamp post  420  being a solid or hollow longitudinal member that perpendicularly extends from the recess external surface  415 . The clamp post  420  being a longitudinal member having a diameter, a height, a first end and a second end. The first or second end being coupled to the recess external surface  415 , and the first or second having a planar surface, the planar surface abutting or mating within a planar surface of the clamp body. The recess  413  comprising a cross-sectional shape and a height  421 . The recess  413  cross-sectional shape is configured to match or substantially match the clamp body (not shown) of the locking mechanism  404 . The recess height  421  being equal to a clamp body width to provide a flush surface, or the recess height being greater than the clamp body width to allow the clamp body to be slightly recessed. Accordingly, the top portion  411  of the second or back shell  401  comprises one or more openings  402  giving rise to one or more crumple zones  407 .  FIGS.  40 E- 40 F  depict a top and bottom view an alternate embodiment of a top portion of a second or back shell. 
     The side portions  419  of the second or back shell  401  may be positioned within or near the temporal regions of the wearer, covering the right and left sides of the wearer and/or at least a portion of the wearer&#39;s mandible as shown in  FIG.  4 E- 4 F . The side portions  410  of the second or back shell  401  may comprise one or more alignment protrusion channels  403 , one or more openings  402  that gives rise to one or more crumple zones  407 , and/or any combination thereof The one or more alignment protrusion channels  403  may be molded directly onto the second shell  401  and/or the one or more alignment protrusion channels  403  may be affixed by a separate structure  3703  as shown in  FIGS.  37 A- 37 B . The separate structure  3703  may comprise a base  3704 , and the one or more protrusion channels  3705  extending through the base  3704 , the base  3704  being coupled to the second shell  3702 , allowing the protrusions  318  (see  FIG.  3 F ) to be inserted into the one or more protrusion channels  3705  for controlled sliding and controlled distance. The second shell side portions  419  may further comprise a portion of the ear cover. The ear cover may comprise a portion of the shell that extends proximate to the wearer&#39;s ear for protection. The ear cover may include holes for further securement of a chin strap (not shown). The alignment protrusions  319  (see  FIG.  3 F ) are inserted within the one or more alignment protrusion channels  403  to allow the first shell  301  and the back shell  401  to mate and facilitate the proper alignment to slidably connect at a fixed distance. The slidable fixed distance may range from 1 mm to 40 mm. The alignment protrusion channels  403  having a width and length, the length of the alignment protrusion channel  403  being a range from 1 mm to 40 mm. The second shell  401  side portion  419  may further comprise a plurality of openings  402 , where the openings may provide for ventilation and/or give rise to one or more crumple zones  407 .  FIG.  40 G  depicts a side view of alternate embodiment of a side portion of a second or back shell. 
     Alternatively, the protrusion alignment channels or the alignment guides  403  and the alignment protrusions  319  may be switched. For example, the protrusion alignment channels  403  may be disposed on the first shell  301  rather than the second shell  401 . Accordingly, the alignment protrusions  319  may be disposed on the second shell  401  rather than the first shell  301 . The helmet alignment guides or alignment protrusion channels may be strategically placed onto or within any region of the helmet, including frontal, ridge (or top), and/or the sides (right or left). The helmet alignment guides will help align the front and back shells in the proper position during adjustment. The helmet alignment guides comprise alignment protrusions and alignment guide channels. The alignment protrusions may be disposed onto a least a portion of the first or second shell, the alignment protrusions being sized and configured to fit within the alignment guide channels. The alignment guide channels may be disposed onto a least a portion of the first or second shell, the alignment guide channels having a translation length, the translation length minimizing the total adjustment size of the helmet. The alignment guide channels being sized and configured to receive the alignment protrusions. Once the alignment protrusions mate with the alignment guide channels, the helmet may only be adjusted to the designed translation length. The translation length may be anywhere from 0 inches to 6 inches. 
     Locking Mechanism Assemblies 
     In one embodiment, an adjustable helmet system may comprise a locking mechanism, the locking mechanism being a clamp locking mechanism assembly  601  (see  FIGS.  6 A- 6 B ,  FIGS.  17 A- 17 D ,  FIGS.  18 A- 18 D , and  FIG.  38 I ) or a cam locking mechanism assembly  1101  (see  FIGS.  11 A- 11 J ). The locking mechanism may be integrated within a portion of the front or back shells and/or be modular, which the modularity allows the locking mechanism to be retrofitted to commercially available helmets. The locking mechanism being movable between a first unlocked position which allows the first (or front) and second (or back) shells to slide relative to each other and a second locked position which inhibits the first and second shells from sliding relative to each other. 
       FIGS.  6 A- 6 H ,  FIGS.  17 A- 17 B  and  FIGS.  38 I  depict various views of an alternate embodiment of a clamp locking mechanism assembly. More specifically,  FIGS.  6 A- 6 H  depicts one embodiment of a clamp locking mechanism assembly  601  that comprises at least one clamp lock subassembly  603  and a clamp tongue  602 . The clamp locking assembly  601  will facilitate easy no-tool detachment and securement by using a lever function and may require only a one-handed operation. For example,  FIGS.  17 A- 17 D  illustrate an example of a method to adjust a representative adjustable helmet assembly  1701 . The user or wearer may lift the clamp body  1705  allowing the clamp post  1705  to place a downward compressive force against a portion of the first or second shells  1702 ,  1703  thereby releasing the first and/or second shells  1702 ,  1703  to move relative to each other. Conversely, to secure or lock the clamp locking assembly  1703 , the user or wearer will push the clamp body down  1705  within the cavity allowing the base plate  1707  coupled to the clamp post  1707  to place an upward compressive force to sandwich the at least a portion of the first and second shells  1702 ,  1703  and/or the clamp tongue  1708  and have the plurality of teeth engage with the plurality of recesses to prevent or inhibit movement of the first and second shells  1702 ,  1703 .  FIGS.  17 A-B  and  FIG.  38 I  illustrate cross-sectional views of an alternate embodiment of a clamp locking mechanism assembly. 
       FIGS.  6 I- 6 J  illustrate an exploded isometric view of a clamp locking mechanism  601 . The clamp locking mechanism assembly  601  may comprise at least one clamp lock subassembly  603  and a clamp tongue  602 . The clamp lock subassembly  603  comprises at least one of a clamp housing  608 , a clamp body  607 , clamp post  604 , and/or a base plate  609 . The clamp lock subassembly  603  may further comprise a spring (not shown). Alternatively,  FIG.  38 I  illustrate an exploded side view of a clamp locking mechanism assembly  3801 . The clamp locking mechanism assembly  3801  comprises a clamp body  507 , a plurality of teeth  3804 , a plurality of recesses (not shown), and a clamp post  3805 . The plurality of recesses being disposed an external surface of a clamp tongue  3803 . 
       FIGS.  7 A- 7 H  depict various views of one embodiment of a clamp housing  701 . The clamp housing  701  comprises a clamp housing recess  703  and a plurality of teeth  708 . The clamp housing  701  having a top surface  702  and a bottom surface  709 , at least a portion of the top surface having a clamp housing recess  703  or cavity extending from the top surface  702  below the bottom surface  709 , the cavity or clamp housing recess  703  sized and configured to receive the clamp body  607  (as shown in  FIGS.  6 I- 6 J ), the cavity or champ housing recess  703  having an aperture  704 , the aperture  704  extends through the clamp housing recess top surface  705  to the clamp housing recess bottom surface  707 , the aperture  704  having a width, the width matches or substantially matches a width of a clamp post  604  (as shown in  FIGS.  6 I- 6 J ). The clamp housing recess bottom surface  707  of the clamp housing  701  having a plurality of teeth  708 , the plurality of teeth  708  perpendicularly extending outwardly from the clamp housing bottom surface  707 , the plurality of teeth  708  sized and configured to fit within a portion of a plurality of recesses  1002  on a clamp tongue  1001  (see  FIGS.  10 A- 10 H ). Alternatively, the clamp housing  701  and the clamp tongue  1001  (see  FIGS.  10 A- 10 H ) may reverse some of the engagement features. The clamp housing recess bottom surface  707  may alternatively comprise a plurality of recesses that are sized and configured to receive a plurality of teeth. Furthermore, the clamp housing recess  703  having a clamp recess height (not shown), the clamp recess height is equal to or greater than a clamp body height  807  (see  FIG.  8 E ). The clamp housing  701  may be affixed to the first or second shell and/or it may be integrated within the first or second shell. Desirably, should the clamp housing  701  be integrated within the first or second shell, the clamp housing  701  would be a recessed surface disposed onto an external surface of the first or second shell. 
       FIGS.  8 A- 8 H and  9 A- 9 G  depict various views of one embodiment of a clamp body  801  and a clamp post  901 . The clamp body  801  comprises a lever portion  805 , at least one finger tab  805 , a at least one base portion  804 , an aperture  803 , and/or any combination thereof The clamp body  801  is sized and configured to fit within and/or disposed within the clamp housing cavity or the clamp housing recess  703  (see  FIG.  7 B ). The at least one finger tab  805  extends longitudinally from the lever portion  805 , the longitudinal extension is on a plane that is parallel and/or substantially parallel to the lever portion  805 . The at least one base  804  having a base channel  806  that extends perpendicularly through the at least one base  804 . The base channel  806  having a base channel width  808  that matches or substantially matches the clamp post width top portion  906  of the clamp post top portion  902 . The clamp body further comprising a clamp body aperture  803 , the clamp body aperture  803  aligns with the clamp post aperture  904  or is concentric with the clamp post aperture  904 . The clamp post  901  being pivotally connected to the clamp body  801  allowing for a lever action or function. 
       FIGS.  16 A- 16 F  and  FIGS.  41 A- 41 G  depict various views of an alternate embodiment for a clamp body. More specifically,  FIGS.  41 A- 41 G  depict a clamp body  4101 , the clamp body  4101  comprises a lever portion  4102 , a base  4103 , at least one aperture  4104 , and at least one channel  4108 . The clamp body  4101  is sized and configured to fit within and/or disposed within the clamp housing cavity or the clamp housing recess  703  (see  FIG.  7 B ). The lever portion  4102  of the clamp body  4101  having a plurality struts that form a matrix or a framework to provide support to the clamp body  4101  and to resist compression or other impacts. Each of the plurality struts are an elongated column. A first plurality of struts are positioned longitudinally along an axis of the clamp body  4101 , and a second plurality of struts are positioned perpendicular to the longitudinal axis of the clamp body  4101 . The at least one base  4103  having a base channel  4105  that extends perpendicularly through the at least one base  4103 . The at least one base  4103  extending perpendicularly below the lever portion  4102 . The base channel  4105  having a base channel width  4106  that matches or substantially matches the clamp post width  4206  first end  4204  of the clamp post top portion  4202 . The clamp body further comprising a clamp body aperture  4104 , the clamp body aperture  4104  aligns with the clamp post aperture  4209  or is concentric with the clamp post aperture  4209 . The clamp post  4201  being pivotally connected to the clamp body  4101  allowing for a lever action or function. 
       FIGS.  9 A- 9 G  illustrates various views of one embodiment of a clamp post  901 . The clamp post  901  comprising a clamp post top portion  902  and a clamp post bottom portion  903 . The clamp post top portion  902  and the clamp post bottom portion  903  having a cross-sectional shape. The cross-sectional shape is circular, and/or it may be hollow. Other cross-sectional shapes may be contemplated, including square and rectangular. The clamp post having a T-shape, where the clamp post top portion  902  is perpendicular to the clamp post bottom portion  903  forming the T-shape. The clamp post  901  having an end with a planar surface  905 , the planar surface abuts or is coupled to the base plate (not shown). 
       FIGS.  42 A- 42 H  illustrates various views of an alternate embodiment of a clamp post  4201 . The clamp post  4201  comprising a clamp post top portion  4102  and a clamp post bottom portion  4203 . The clamp post top portion  4202  and the clamp post bottom portion  4203  having a cross-sectional shape. The clamp post top portion  4202  cross-sectional shape is generally rectangular. The clamp post top portion  4202  extends perpendicular to the base  4203 . The clamp post top portion  4202  having a first end  4204  and a second end  4205 , the second end  4205  coupled to the clamp post bottom portion  4203 . The first end  4204  having a cylindrical shape, the first end  4204  having a width  4206 . The width  4206  of the first end  4204  of the clamp post top portion  4202  that matches or substantially matches the base channel  4105  of the clamp body  4101  (see  FIGS.  41 A- 41 G ). The clamp post bottom portion  5203  cross-sectional shape is rectangular or generally rectangular, but other shapes may be contemplated, including square, circular or triangular. The clamp post bottom portion  5203  having a first surface  4207  and a second surface  4208 , the second surface  4208  having a plurality of ribs  4209  extending along at least a portion of the length of the clamp post bottom portion  4203 . The plurality of ribs  4209  extending parallel or perpendicularly below the second surface  4208 . The first surface  4207  abuts and/or mates with at least a portion of the first surface  1004  or second surface  1005  of the clamp tongue  1001  (see  FIGS.  10 A- 10 H or  38 I ) and/or the bottom surface of a clamp tongue. 
       FIG.  10 A- 10 H  depicts various views of an alternate embodiment of a clamp tongue  1001 . The clamp tongue  1001  having a longitudinal body, at least a portion of the longitudinal body angled obliquely between a range of 1 degree to 60 degrees. The clamp tongue having a first surface  1004  and a second surface  1005 , at least a portion of the first surface  1004  or second surface  1005  including a plurality recesses  1002 , the plurality of recesses  1002  sized and configured to receive a portion of the clamp housing plurality of teeth  703  (see  FIG.  7 A ), the clamp tongue  1001  further comprising a clamp tongue channel  1003 , the clamp tongue channel  1003  extends through the first surface  1004  to the second surface  1005 , the clamp tongue channel  1003  having a clamp channel width  1006 , the clamp channel width  1006  being sized and configured to receive the clamp post bottom portion  903  (see  FIGS.  9 A- 9 G ) and/or the clamp channel width  1006  matching or substantially matching the clamp post bottom portion width and/or cross-sectional shape. The clamp channel  1003  having a channel length  1007 , the channel length  1007  allowing clamp post  901  to translate axially, the translation distance being 1 mm to 25 mm. The clamp post coupled to a base plate. 
     Alternatively, the clamp housing  701  (see  FIG.  7 A- 7 H ) and the clamp tongue  1001  (see  FIGS.  10 A- 10 H ) may reverse some of the engagement features. The clamp housing recess bottom surface  707  may alternatively comprise a plurality of recesses that are sized and configured to receive a plurality of teeth. Furthermore, the clamp housing recess  703  having a clamp recess height (not shown), the clamp recess height is equal to or greater than a clamp body height  807  (see  FIG.  8 E ). The clamp housing  701  may be affixed to the first or second shell, and/or the clamp tongue  1001  may be affixed to the first or second shell. The clamp tongue  1001  having a first surface  1004 , a second surface  1005  and a clamp channel  1003 . The clamp tongue first surface  100  having a plurality of a plurality teeth  703  disposed onto the first surface  1004 , at least a portion of the plurality of recesses  1002  disposed on the clamp housing  701  are sized and configured to receive a portion of a plurality of teeth  703 , the clamp channel  1003  sized and configured to receive a clamp post  901 . 
       FIGS.  11 A- 11 H  depicts various views of one embodiment of a cam locking mechanism assembly  1101 . The adjustable helmet system may comprise a first shell, a second shell and a locking mechanism assembly, the locking mechanism assembly comprises a cam locking mechanism  1101 . The cam locking mechanism  1101  may comprise a cam tongue  1102  and a cam locking subassembly  1103 . The cam locking assembly  1101  will facilitate easy no-tool detachment and securement by using a rotation action and may require only a one-handed operation. To adjust a representative helmet, the user or wearer may rotate the cam body allowing the cam post to place a downward compressive force against a portion of the first or second shells thereby releasing the first and/or second shells to move relative to each other. Conversely, to secure or lock the cam locking assembly, the user or wearer will rotate the cam body in the opposite direction allowing the base plate coupled to the cam post to place an upward compressive force to sandwich the at least a portion of the first and second shells and prevent or inhibit movement and have the plurality of teeth engage with the plurality of recesses. 
       FIGS.  11 I- 11 J  depict an exploded isometric and side view of one embodiment of a cam lock mechanism  1101 . The cam lock mechanism  1101  comprises a cam tongue  1102  and a cam locking subassembly  1103 . The cam locking subassembly  1103  comprises a cam housing  1104 , a cam post  1105 , a base plate  1107 , a cam body  1106 , and/or any combination thereof 
       FIGS.  12 A- 12 H  depict various views of one embodiment of a cam tongue  1201 . The cam tongue  1201  having a longitudinal body, at least a portion of the longitudinal body having an arched shape or a generally arched shape. The cam tongue  1201  having a first surface  1202  and a second surface  1203 , at least a portion of the first surface  1202  or second surface  1203  including a plurality recesses  1204 , the plurality of recesses  1204  sized and configured to receive a portion of the cam housing plurality of teeth  1303  (see  FIG.  13 A ), the cam tongue  1201  further comprising a clamp tongue channel  1205 , the cam tongue channel  1205  extends through the first surface  1202  to the second surface  1203 , the cam tongue channel  1205  having a cam channel width  1206 , the cam channel width  1206  being sized and configured to receive the cam post top portion  1402  (see  FIGS.  14 A- 14 G ) and/or the cam channel width  1206  matching or substantially matching the cam post top portion width and/or cross-sectional shape. The cam channel  1203  having a channel length  1207 , the channel length  1207  allowing cam post  1401  to translate axially, the translation distance being 1 mm to 25 mm. The cam post coupled to a base plate. The cam tongue  1201  may be positioned and/or coupled on the top portion of the front or back shell, and extend longitudinally away from the top portion of the front or back shell. 
     Alternatively, the cam tongue  1201  and/or the front or back shells may reverse some of the engagement features. The cam tongue  1201  having a first surface  1202  and a second surface  1203 , at least a portion of the first surface  1202  including the plurality teeth, the plurality of teeth sized and configured to fit within a plurality of recesses with a front or back shell top portion second surface, the cam tongue having a channel  1203 , the channel  1203  extends through the first surface  1202  to the second surface, the channel  1203  sized and configured to receive the cam post  1401 ; the channel having a length, the length allowing cam post  1401  to translate along an axis. 
       FIGS.  13 G- 13 H  depict various views of one embodiment of a cam housing  1301 . The cam housing  1301  comprises a clamp housing recess  1302  and a plurality of teeth  1203 . The cam housing  1301  having a top surface  1304  and a bottom surface  1305 , at least a portion of the top surface  1304  having a cam housing recess  1302  or cavity starting from the top surface  1304  and extending below the bottom surface  1305 , the cavity or cam housing recess  1302  sized and configured to receive the cam body  1501  (as shown in  FIGS.  15 A- 15 H ), the cavity or cam housing recess  1302  having an aperture  1306 , the aperture  1306  extends through the cam housing recess top surface  1307  to the cam housing recess bottom surface  1308 , the aperture  1306  having a width, the width matches or substantially matches a width of a cam post top portion  1402  (as shown in  FIGS.  14 A- 14 H ). The cam housing recess bottom surface  1308  of the cam housing  1301  having a plurality of teeth  1303 , the plurality of teeth  1303  perpendicularly extending outwardly from the cam housing bottom surface  1308 , the plurality of teeth  1303  sized and configured to fit within a portion of a plurality of recesses  1002  on a cam tongue  1301  (see  FIGS.  10 A- 10 H ). 
     Alternatively, the cam housing  1301  and the camp tongue  1201  (see  FIGS.  12 A- 12 H ) may reverse some of the engagement features. The cam housing recess bottom surface  1308  may alternatively comprise a plurality of recesses  1204  (see  FIG.  12 A- 12 H ) that are sized and configured to receive a plurality of teeth  1303 . Furthermore, the cam housing recess  1302  having a cam recess height (not shown), the cam recess height is equal to or greater than a cam body height  1507  (see  FIG.  15 F ). The cam housing  1301  may be affixed to the first or second shell. 
       FIGS.  14 A- 14 H  depict various views of one embodiment of a cam post  1401 . The cam post  1401  comprising a cam post top portion  1402  and a cam post bottom portion  1403 . The cam post top portion  1402  having a cam post top portion cross-sectional shape. The cam post top portion cross-sectional shape includes circular, and/or it may be hollow. Other cross-sectional shapes may be contemplated, including square and rectangular. The cam post top portion  1402  may have a channel  1404  that extends from the first end  1405  of the cam post top portion  1402  towards a portion of the second end  1406  of the cam post top portion  1402 . At least a portion of the channel  1404  may be chamfered. The cam post having a T-shape, where the cam post top portion  1402  is a longitudinal member that perpendicularly extends upward from the cam post bottom portion  1403  forming the T-shape. The cam post second end  1406  having an end with a planar surface, the planar surface abuts or is coupled to the cam post bottom portion  1403 . 
       FIGS.  15 A- 15 H  depict various views of one embodiment of a cam body  1501 . The cam body  1501  comprises a first portion  1502 , a second portion  1503 , an aperture  1504 , and/or any combination thereof The cam body  1501  is sized and configured to fit within and/or disposed within the cam housing cavity or the clamp housing recess  1302  (see  FIG.  13 B ). The first portion abuts or mates with the cam housing top surface  1307 . The second portion  1503  having a longitudinal member that extends perpendicularly first portion  1502 . The second portion  1503  may further comprise a top surface, the top surface having a recess  1506  disposed within. The second portion  1503  may further comprise ribs  1504 , the ribs  1504  having a generally triangular shape. Other shapes may be contemplated, including square or rectangle. The ribs  1504  are intended to allow the wearer to have sufficient surface area to hold the cam body  1501  and rotate. The aperture  1504  having a width that matches or substantially matches the cam post width top portion  1402  of the cam post  1401 . The cam post  1501  being inserted to the cam body  1401  allowing for a rotation action or function. 
     In another embodiment, the adjustable helmet system may have an alternate embodiment of an integrated locking mechanism. The adjustable helmet comprises a first shell, the first shell having an external surface and an internal surface; a second shell, the second shell being slidably attached to the first shell, the second shell an external surface and an internal surface; and a locking mechanism, the locking mechanism including: a clamp tongue, clamp tongue extending away from the first or second shell, the clamp tongue having a plurality of a plurality recesses, at least a portion of the plurality of recesses are sized and configured to receive a portion of a plurality of teeth; a plurality of teeth, at least a portion of the plurality of teeth sized and configured to fit within a portion of the plurality of recesses, the plurality of teeth disposed on a portion of the first or second shell internal surfaces; and a clamp assembly, the clamp assembly being movable between a unlocked position that disengages the portion of the plurality of teeth from the portion of the plurality of recesses and allow the first and second shells to slide relative to each other, and a locked position that allows the a portion of the plurality of teeth and a portion of the plurality of recesses to engage that inhibits the first and second shells from sliding relative to each other. The adjustable helmet may further comprise a cavity, the cavity being sized and configured to receive the clamp assembly, the cavity being disposed within the first or second shells, the clamp assembly having a top surface and a bottom surface, the clamp assembly top surface being flush or substantially flush with the external surface of the first or second shell. 
     In another embodiment, the adjustable helmet system may have an alternate embodiment of an integrated locking mechanism. An adjustable helmet comprising: a first shell, the first shell having an external surface and an internal surface; a second shell, the second shell being slidably attached to the first shell, the second shell an external surface and an internal surface; and a locking mechanism, the locking mechanism including; and a clamp assembly, the clamp assembly having a clamp body, the clamp post, and a base plate; a clamp tongue, clamp tongue extending away from the first or second shell, the clamp tongue having a top surface, a bottom surface and a first channel, the clamp tongue top surface having a plurality of a plurality recesses, at least a portion of the plurality of recesses are sized and configured to receive a portion of a plurality of teeth, the channel sized and configured to receive the clamp post; a plurality of teeth, the plurality of teeth disposed on a portion of the first or second shell internal surface, at least a portion of the plurality of teeth sized and configured to fit within a portion of the plurality of recesses, the first or second shell internal surface further including a second channel, the second channel sized and configured to receive the clamp post; a cavity, the cavity being sized and configured to receive the clamp assembly, the cavity being disposed within the first or second shells external surface, the clamp assembly having a top surface and a bottom surface, the clamp assembly top surface being flush or substantially flush with the external surface of the first or second shell, the cavity having an aperture, the aperture sized and configured to receive the clamp post; the base plate coupled to the clamp post, the base plate abuts the bottom surface of the clamp tongue; a clamp assembly, the clamp assembly being movable between a locked position and an unlocked position, the locked position places tension on the clamp post and the base plate to compress the clamp tongue allowing a portion of the plurality of teeth and a portion of the plurality of recesses on the clamp tongue to engage and inhibit the first and second shells from sliding relative to each other, the unlocked position places compression on the clamp post and the base plate to release the clamp tongue allowing the portion of the plurality of teeth and the portion of the plurality of recesses of the clamp tongue to disengage, and allow the first and second shells to slide relative to each other. 
     Ear Protection and Other Accessories 
       FIGS.  1 A- 1 G and  19    depict different embodiments of adjustable helmet assemblies that include ear protection  1901 . In one embodiment, adjustable helmet system may further comprise ear protection  1901 . The ear protection  1901  may comprise a base  1905  and an ear frame  1902 . The base  1905  may have an exterior surface  1907  and an interior surface  1906 . The ear frame  1902  having a shape that relatively matches or substantially matches or matches the wearer&#39;s ear. The ear frame  1902  may extend perpendicularly away from the base  1905  exterior surface  1907  to have a slight protrusion. The ear frame  1902  may include a recessed perimeter  1903 , where the recessed perimeter  1903  may relatively matches or substantially matches or matches the wearer&#39;s ear, and the wearer&#39;s ear may be seated or abut against the recessed perimeter  1903 . The ear frame  1902  may further comprise an aperture  1908  therethrough, the aperture  1908  is sized and configured to substantially match or reasonably match around a wearer&#39;s ear canal to allow sound to easily penetrate and pass through. At least a portion of the ear protection  1901  is coupled to a first shell, and at least a portion of the ear protection  1901  is coupled to a second shell. Alternatively, the ear protection  1901  may be coupled to the first or second shell. Ear protectors may general offer protection around the temporal region of the wearer&#39;s head.  FIGS.  43 A- 43 F  depict various views of an alternate embodiment of an ear protection. 
       FIGS.  1 A- 1 G  and  FIG.  44 A- 44 F  depict an exploded view of an adjustable helmet assembly that comprises an ear loop. In one embodiment, the adjustable helmet system may further comprise an ear loop  4401 . The ear loop  4401  may comprise a frame that extends away from the edge of the helmet downwards away from the ear towards the jaw and/or mandible region of the wearer&#39;s head to overlap a portion of the jaw and/or mandible region. The ear loop  4401  may follow the contours of the jaw and/or mandible region of the wearer&#39;s head. Such ear loop  4401  comprises a first member  4402  and a second member  4403 , the first  4402  and second  4403  member having a length, the length being average or median jaw length. The first member  4402  may be coupled to the first or second shell (not shown), the second member  4403  may be coupled to the first or second shell (not shown). Each of the first member  4402  and the second member  4403  having first end and a second end. Each of the first member  4402  and the second member  4403  first end  4404 ,  4405  having a connecting structure  4406 , the connecting structure  4406  having a square or rectangle cross-sectional shape, the connecting structure  4406  have a width greater than the first member  4402  and the second member  4403  width. Furthermore, the second ends of the first member  4402  and the second member  4403  being coupled together. The ear loop  4401  may be fixed, and/or removably connected. The ear loop  4401  is generally U-shaped. The ear loop may further comprise a pad. The pad may comprise at least one foam layer. The pad may further comprise an impact mitigation structure. 
       FIGS.  1 A- 1 G  depict an exploded view of an adjustable helmet assembly that further comprises a chin strap. Such chin strap may allow the wearer&#39;s head to be secured to the helmet to prevent premature dislodgement of the helmet during impact. The chin strap may be removably coupled to the first and/or second shells. The chin strap may further comprise a pad. The pad may comprise at least one foam layer. The pad may further comprise an impact mitigation structure. 
       FIGS.  1 A- 1 G  depict an exploded view of an adjustable helmet assembly that further comprises a visor. Such visor may be affixed to the first and/or second shell to protect players from glare or eye injuries. Furthermore, the visor may comprise protective coatings, such as scratch-resistance, UV coating, anti-glare coating, and/or any combination thereof. 
     Openings and Crumple Zones 
     In one exemplary embodiment, the adjustable helmet assembly may comprise one or more openings that gives rise to one or more crumple zones. Crumple zones are areas of the adjustable helmet assembly that are designed to deform in a controlled manner during an impact. The specifically designed crumple zones would absorb some of the impact force and redistribute the impact force before its transmitted to the wearer. More specifically, there&#39;s a given amount of force present during any impact, and the forces are determined by the acceleration and the mass of the wearer or the objects causing the impacts. Therefore, in order for the crumple zones to absorb and redistribute the impact force, it may do this by slowing down the acceleration or by extending the distance over which the adjustable helmet&#39;s kinetic energy is transferred out (into potential or thermal energy). The acceleration may be slowed by creating one or more crumple zones around the perimeter of the adjustable helmet, which the crumple zones would take the initial impact, slowing down acceleration by a few tenths of a second to create a drastic reduction in the force involved during an impact. Accordingly, crumple zones may be manufactured and integrated directly into the adjustable helmet and/or be commercially available (CA) helmet may be retrofitted with crumple zones. 
       FIGS.  20 A- 20 I  depict one various views of alternate embodiments of an adjustable helmet  2001  with integrated crumple zones. In one embodiment, the adjustable helmet  2001  may comprise one or more openings  2002 ,  2003  that may be disposed onto a front shell  2004  and/or a back shell  2005 . Such one or more openings  2002 ,  2003  may align with the front shell  2004  and/or a back shell  2005 . Such one or more openings  2002 ,  2003  may an elongated cross-sectional shape, such that each of the one or more openings  2002 ,  2003  have a length and a width. The length and/or the width of the one or more openings  2002 ,  2003  may allow particular regions and/or localized regions of the adjustable helmet  2001  to bend, deflect and/or collapse as shown in  FIGS.  20 D- 20 I . The width may be a range between 0.0625 inches to 2 inches, and the length may have a range between 0.25 inches to 5 inches. The elongated cross-sectional shape of the one or more openings  2002 ,  2003  may follow the contours of helmet. For example, in one embodiment, a unilateral or bilateral lateral force  2010  may impact the adjustable helmet  2001  leading to a localized bending and/or deflecting  2011  one or both sides of the adjustable helmet  2001  as shown in  FIGS.  20 D- 20 E . In another embodiment, a normal or axial force  2012  may impact the adjustable helmet  2001  leading to a localized bending, deflecting, collapse and/or buckling  2013  of the specific regions of the adjustable helmet  2001  as shown in  FIGS.  20 F- 20 G . Accordingly, in another embodiment, an oblique force  2014  may impact the adjustable helmet  2001  leading to a localized bending, deflecting, collapse and/or buckling  2015  of the specific regions of the adjustable helmet  2001  as shown in  FIGS.  20 H- 20 I . 
     The at least one opening  2002 ,  2003  placed adjacent to, in proximity to or within impact zones and/or crumple zones of the first shell  2004  or second shells  2005  resulting in absorption of the energy from the impact by controlled local deformation and/or reducing the impact forces transferred to the head of the wearer. The impact zones are zones of a wearer&#39;s head that may see higher than normal frequency of impacts and/or magnitude of impacts. The impact zones are within the occipital region (lower and mid), temporal region (right and left side), parietal region, orbit region, the frontal region, the mandible (front, right and/or left side) region, the maxilla region, the nasal region, zygomatic region, the ethmoid region, the lacrimal region, the sphenoid region, crown region or top ridge, raised eyebrow region and/or any combination thereof. In addition, the at least one opening may provide ventilation allowing air to circulate around the head of the wearer. The at least one opening may be positioned in plane tangent to the helmet circumference, in a plane perpendicular or substantially perpendicular to the helmet circumference, or in an oblique plane to the helmet plane, in a plane parallel to helmet plane, and/or any combination thereof. 
     Furthermore, the one or more openings  2002 ,  2003  may have one or more tabs  2006  disposed within the one or more openings  2002 ,  2003  to further absorb the impact forces. The one or more tabs  2006  couple the center plate  2007  to the top portion  2008  of the front shell  2004  and/or the back shell  2005 . The one or more tabs  2006  may be desirably used to provide a controlled deformation and/or buckling. The one or more tabs  2006  may span the width of the one or more openings  2002 ,  2003 . The one or more tabs  2006  may have a length, width and depth, as well as a cross-sectional shape that facilitates a controlled deformation response by providing some relative resistance. Such cross-sectional shape can vary, and includes square, rectangle, triangle, hexagon, dome or arched cross-sectional shape, and/or any combination thereof The desired cross-sectional shape would improve on the specific deformation properties that are expected for the adjustable helmet design. The length, width and/or depth of the one or more tabs  2006  may vary to obtain the ideal tab structure that can provide such controlled deformation, and still allow return to its original configuration. Alternatively, different protrusions  2009  may be positioned within the center plate  2007  and/or other locations on the adjustable helmet  2001  that may also further facilitate impact absorption. 
       FIGS.  22 A- 22 B,  23 ,  24 A- 24 F,  25 ,  26 A- 26 B and  27    depict various views of alternate embodiments of helmets with retrofitted crumple zones. Various types of traditional commercially available (CA) helmets  2101  have very pronounced shell features that are purely aesthetic. Many of these features contain shell protrusions  2102  on the outer helmet layer or shell as shown in  FIGS.  21 A- 21 F , where the shell protrusions  2102  may have an empty cavity that faces internally towards the wearer&#39;s head and protrude outwardly away from the exterior surface of the outer shell. The CA helmets  2101  may have at least one shell protrusion  2102  with empty cavities are in various regional locations that are configured in varying sizes and shapes throughout the helmet outer layer structure. 
     Furthermore, the shell protrusions  2102  provide many disadvantages to the player that decides to wear such a CA helmet  2101 . The disadvantages provide (1) additional unnecessary weight to the CA helmet; (2) The shell protrusions have cavities that is considered unused real estate; (3) the shell protrusions do not provide any impact protection (see  FIG.  2 B ); and (4) the impact will be directly transferred to the players head potentially at the same acceleration as the impact, and not properly distributed over a wide an area as possible to reduce the deformation and severity of impact (see  FIG.  2 B ). 
     As a result, the present invention overcomes many of the disadvantages observed with current CA helmets  2101 . The present invention relates to various methods, devices and systems to retrofit CA helmets to leverage the existing shell protrusions and its cavities to improve impact performance of the CA helmet  2101 . Impact performance may be improved by modifying or retrofitting the shell protrusions  2102  with impact mitigation structures and/or impact mitigation features to create crumple zones. 
     By leveraging at least one shell protrusion  2102  on the CA helmet  2101 , the at least one shell protrusion  2102  may be deformable, bendable, deflectable, collapsible or compressible or buckle, behaving similarly to “crumple zones.” The at least one shell protrusion  2102  may be designed with impact mitigation structures and/or impact mitigation features to essentially convert the at least one shell protrusion to a crumple zone. The crumple zones will be defined as at least one shell protrusion that is converted into an impact structural area located in various regions on the CA helmet that facilitate the management of incident forces on the helmet during play, thus enhancing protection from the localized impact directly to the player&#39;s head in a predictable manner. Furthermore, such crumple zones can collapse, deform and/or compress in a predictable way to absorb much of the impact kinetic energy by reducing the initial impact force and redistribute the impact force before it reaches the player&#39;s head. 
       FIGS.  22 A- 22 B  depict cross-sectional views of one embodiment of a traditional CA helmet  2201  with protrusions. The CA helmet  2201  may comprise an outer shell or outer layer  2202 , the outer layer having an outer surface  2207  and an inner surface  2208 , a shell protrusion  2203  that extends outwardly from the outer surface  2207  of the outer layer  2202 . The shell protrusion  2203  may have a cavity  2204  disposed within, the cavity  2204  may face towards the head of the wearer  2206 . The shell protrusion  2203  does not contain any features, cross-sectional shape or other material changes that would provide or lead to a crumple zone. A force  2209  may impact the CA helmet  2201  causing the rigid protrusion  2203  to transmit the force directly to the wearers head  2206 , leading to increased concussions and/or other brain injuries.2 
       FIG.  23    depicts a cross-sectional view of one embodiment of CA helmet  2301  that comprises a shell protrusion  2302  with impact mitigation features  2303  to create one or more crumple zones. The CA helmet  2301  may comprise an outer layer  2302 , an impact mitigation layer  2304  and/or at least one protrusion  2302 . The at least one CA helmet shell protrusion  2302  may be modified with impact mitigation features  2303  that allow the deformation, collapsibility, compressibility, buckling and/or impact absorption desired for the particular wearer, the wearer&#39;s position, and/or the wearer&#39;s sport or occupation. The impact mitigation features  2304  may comprise a plurality of perforations, the plurality of perforations extending therethrough from the outer surface of the outer shell protrusion  2302  through to the inner surface of the outer shell protrusion  2302 , thus creating a through-hole perforation. The plurality of perforations may be symmetrically aligned or be offset. 
     The plurality of perforations may include a variety of different shapes and/or configurations to enhance deformation, collapsibility, compressibility, buckling and/or impact absorption as shown in  FIGS.  24 A- 24 F . Such shapes and/or configurations may include relief cuts, slits, holes, openings, polygons  2401 ,  2042 , herringbone shape  2406 , zig-zag shapes  2404 , chevron shapes  2405 , auxetic shapes (not shown), reentrant shapes  2403 , and/or any combination thereof It should be understood that any shape and configuration can be contemplated as long as the impact mitigation feature facilitates or improves impact performance. 
       FIG.  25    depicts a cross-sectional view of an alternate embodiment of a CA helmet retrofitted with a crumple zone. The CA helmet  2501  may comprise an outer layer  2502 , an impact mitigation layer  2505 , at least one shell protrusion  2503 , and an impact mitigation structure  2504 . The at least one CA helmet shell protrusion  2503  may incorporate at least one impact mitigation structure  2504  over the shell protrusions  2503 . The at least one impact mitigation structure  2504  can be affixed to the outer surface of the shell protrusion  2503 . Affixation may be a removable affixation or a permanent affixation. Affixation may use various methods known in the art, including press-fit, friction-fit, snaps, Velcro, magnets, adhesives, molding, sintering, welding, cam locks, screws and bolts, dovetail, interlocking protrusions (e.g. LEGOs), over molding and/or any combination thereof. Each of these coupling mechanisms may utilize existing features of a CA helmet or may require minor modifications with penetration through at least one of the CA helmet outer layer, CA helmet inner layer, the CA impact absorbing layer, and/or any combination thereof. 
       FIGS.  26 A- 26 B  depicts a cross-sectional view of an alternate embodiment of CA helmet retrofitted with a crumple zone. The CA helmet  2601  may comprise an outer layer  2602 , an impact mitigation layer  2605 , at least one shell protrusion  2603 , and an impact mitigation structure  2604 . The at least one CA helmet shell protrusion  2603  may be replaced with at least one impact mitigation structure  2604 . The at least one impact mitigation structure  2604  may match or substantially match the shape of the at least one shell protrusion  2603 . The at least one CA helmet shell protrusion  2603  may be removed with methods known in the art leaving an opening or empty space ( FIG.  26 A ). The at least one impact mitigation structure  2604  may mimic the shape and/or configuration of the existing, removed shell protrusion  2603  or redesigned to desired custom shape &amp; configuration. The at least one impact mitigation structure  2604  may be disposed within the opening and/or over the opening and affixed to the CA helmet. The affixation may be a removable affixation or a permanent affixation. Affixation may use various methods known in the art, including press-fit, friction-fit, snaps, Velcro, magnets, adhesives, molding, sintering, welding, cam locks, screws and bolts, dovetail, interlocking protrusions (e.g. LEGOs), over molding and/or any combination thereof Each of these coupling mechanisms may utilize existing features of a CA helmet or may require minor modifications with penetration through at least one of the CA helmet outer layer, CA helmet inner layer, the CA impact absorbing layer, and/or any combination thereof. 
       FIG.  27    depicts a cross-sectional view of an alternate embodiment of CA helmet retrofitted with a crumple zone. The CA helmet  2701  may comprise an outer layer  2702 , an impact mitigation layer  2705 , at least one shell protrusion  2703 , and an impact mitigation structure  2704 . The at least one CA helmet shell protrusions  2703  may have at least one impact mitigation structure  2704  disposed within the cavity of the shell protrusion  2703 . The at least one impact mitigation structure  2704  may mimic the shape and/or configuration of the existing shell protrusion  2603  and may partially fill the cavity. The at least one CA helmet impact mitigation layer  2705  may be removed to access the CA helmet shell protrusion cavity. The at least one impact mitigation structure may be affixed to the shell protrusion cavity. Affixation may be a removable affixation or a permanent affixation. Affixation may use various methods known in the art, including press-fit, friction-fit, snaps, Velcro, magnets, adhesives, molding, sintering, welding, cam locks, screws and bolts, dovetail, interlocking protrusions (e.g. LEGOs), over molding and/or any combination thereof Each of these coupling mechanisms may utilize existing features of a CA helmet or may require minor modifications with penetration through at least one of the CA helmet outer layer, CA helmet inner layer, the CA impact absorbing layer, and/or any combination thereof 
       FIG.  45    depict a cross-sectional front view of a helmet with crumple zones. An helmet  4501  comprising an impact mitigation layer; the impact mitigation layer having a first portion  4504  and a second portion  4505 ; and an outer shell, the outer shell having a first region  4502  and a second region  4503 , at least a portion of the outer shell first region  4502  being in contact with the impact mitigation layer first portion  4502 , the outer shell second region  4503  being in contact with the impact mitigation layer second portion  4505 , at least a portion of the outer shell first region  4502  being offset from a portion of the outer shell second region  4503 , at least a portion of the outer shell second region  4503  being independently deflectable relative to at least a portion of the outer shell first region  4502  as shown in  FIGS.  20 A- 20 I . The outer shell comprises a front shell and a back shell. The offset comprises at least one or more openings, and/or one or more tabs. Alternatively, the one or more tabs may be disposed with the one or more openings, the one or more tabs span the width of the one or more openings. 
     Impact Mitigation Layer and Impact Mitigation Structures 
     In another embodiment, the adjustable helmet system assembly may further comprise an impact mitigation layer. The adjustable helmet system includes a helmet, a locking mechanism, and/or an impact mitigation layer. The helmet may comprise a front shell (or first shell) and a back shell (or second shell), the first or second shell having an external surface and an internal surface. The locking mechanism, being movable between a first unlocked position which allows the first and second shells to slide relative to each other and a second locked position which inhibits the first and second shells from sliding relative to each other. The impact mitigation layer may comprise at least one impact mitigation structure. The impact mitigation layer may further comprise a force distribution layer, the force distribution layer being a relatively rigid or rigid material. The impact mitigation structure may comprise a first portion and a second portion. The first portion and second portion may comprise the same impact mitigation structure or different impact mitigation structures. The impact mitigation layer may be coupled to a first and/or second shell internal surface. Coupling may occur in different regions within the first or second shell and the coupling may comprise heat staking, gluing, mechanical mounting, Velcro, and/or any combination thereof. The impact mitigation structures may comprise at least a portion of filaments ( FIGS.  28 A- 28 D ), at least a portion of laterally supported filaments (LSFs) ( FIGS.  29 A- 29 C and  30 A- 30 C ), at least a portion of auxetic structures ( FIGS.  31 A- 31 B ), at least a portion of liner pod assemblies ( FIGS.  34 A- 34 B and  35 A- 35 B ), TPU (not shown), undulating structures ( FIGS.  24 D- 24 F ), inflatable bladders (not shown), shock bonnets (not shown), at least one foam layer, and/or any combination thereof. 
     Furthermore, as disclosed herein, any CA helmet with at least one shell protrusion may be leveraged to create or enhance impact protection by converting the at least one shell protrusion into crumple zones or impact zones. The at least one shell protrusion may be converted into a crumple zone or impact zone by incorporating impact mitigation features or impact mitigation structures that allow the collapsibility, compressibility and/or impact absorption. The impact mitigation structures may comprise at least a portion of filaments ( FIGS.  28 A- 28 D ), at least a portion of laterally supported filaments (LSFs) ( FIGS.  29 A- 29 C and  30 A- 30 C ), at least a portion of auxetic structures ( FIGS.  31 A- 31 B ), at least a portion of liner pod assemblies ( FIGS.  34 A- 34 B and  35 A- 35 B ), TPU (not shown), undulating structures ( FIGS.  24 D- 24 F ), inflatable bladders (not shown), shock bonnets (not shown), at least one foam layer, and/or any combination thereof. 
     In one embodiment, the impact mitigating structures can comprise at least a portion of filaments.  FIGS.  28 A- 28 D  depicts that at least a portion of filaments may be thin, longitudinally extending members or be shaped and configured to deform non-linearly in response to an impact force. The non-linear deformation behavior is expected to provide improved protection against high-impact forces, and/or oblique forces. The non-linear deformation behavior is described by at least a portion of the filaments stress-strain profile. The non-linear stress-strain profile illustrates that there can be an initial rapid increase in force (region I) followed by a change in slope that may be flat, decreasing or increasing slope (region II), followed by a third region with a different slope (region III). 
     In another embodiment, the at least a portion of the filaments may comprise filaments that buckle in response to an incident force, where buckling may be characterized by a localized, sudden failure of the filament structure subjected to high compressive stress, where the actual compressive stress at the point of failure is less than the ultimate compressive stress that the material is capable of withstanding. Furthermore, the at least a portion of the filaments may be configured to deform elastically, allowing the at least a portion of the filaments to substantially return to their initial configuration once the external force is removed. The at least a portion of filaments may extend between two surfaces, the at least a portion of filaments having at least one end coupled to the outer layer and/or the inner layer. 
     In another embodiment, the impact mitigating structures can comprise at least a portion of a plurality of filaments that are interconnected by laterally positioned walls or sheets in a polygonal configuration, otherwise known as laterally supported filaments (LSF).  FIGS.  29 A- 29 C  illustrate at least a portion of the LSF structures  2901 , where the filaments  2902  are arranged in a hexagonal pattern interconnected by laterally positioned walls  2903 . Alternatively, other polygonal structures and/or configurations known in the art may be contemplated, such as triangular, square, pentagonal, hexagonal, septagonal, octagonal, and/or any combination thereof. A plurality of sheets or lateral walls  2903  can be secured between adjacent pairs of filaments  2902  with each filament having a pair of lateral walls attached thereto. Alternatively, each of the plurality of filaments  2902  may comprise a lateral wall  2903  extending outwardly therefrom to at least one adjacent filament  2902 . In the disclosed embodiment, the lateral walls  2903  can be oriented approximately 120 degrees apart about the filament axis, with each lateral wall extending substantially along the longitudinal length of the filament  2902 . Accordingly, the orientation of the lateral walls  2903  may be asymmetric, which at least one lateral wall  2903  may be oriented approximately 75 to 135 degrees apart about the filament axis. The shape, wall thickness or diameter, height, and configuration of the lateral walls  2903  and/or filaments  2902  may vary as shown in  FIGS.  29 A- 29 C  to “tune” or “tailor” the structures to a desired performance. For example, one embodiment of a hexagonal structure may have a tapered configuration as shown in  FIG.  29 A . The hexagonal structure can have a top surface  2905  and a bottom surface  2904 , with the bottom surface  2904  perimeter (and/or bottom surface thickness/diameter of the individual elements) that may be larger than the corresponding top surface  2905  perimeter (and/or individual element thickness/diameter). In another example, the hexagonal structure can have an upper ridge  2906  as shown in  FIG.  29 C . The upper ridge  2906  can also facilitate connection to another structure, such as an inner surface of a helmet, an item of protective clothing, and/or a mechanical connection (e.g., a grommet or plug having an enlarged tip that is desirably slightly larger than the opening in the upper ridge of the hexagonal element). 
     Furthermore, the polygonal or hexagonal structures  3001  may be manufactured as individual structures or in a patterned array (see  FIGS.  30 A- 30 C ). The individual structures  3001  can be manufactured using an extrusion, investment casting or injection molding process. Also, they may have the same shape and configuration with repeating symmetrical arrangement or asymmetrical arrangement and/or different shape and configurations with repeating symmetrical arrangement or asymmetrical arrangement. 
     Conversely, the polygonal or hexagonal structures  3001  may be manufactured directly into a patterned array that is affixed to at least one base membrane  3002 . The base membrane may be manufactured with a polymeric or foam material. The polymeric or foam material may be flexible and/or elastic to allows it to be easily bent, twisted or flexed to conform to complex surfaces. Alternatively, the polymeric and/or foam material may be substantially rigid. The manufacturing of each patterned array of polygonal or hexagonal structures  3001  may include extrusion, investment casting or injection molding process. The base membrane with the polygonal or hexagonal structures may be affixed directly to at least a portion of the base or the entirety. Affixing each pattered array of polygonal or hexagonal structures  3001  may be arranged in continuous or segmented arrays. Also, the polygonal or hexagonal structures  3001  may have the same shape and configuration with repeating symmetrical arrangement or asymmetrical arrangement and/or different shape and configurations with repeating symmetrical arrangement or asymmetrical arrangement. 
     In another embodiment, the impact mitigation structure may comprise at least a portion of auxetic structures  3101  as shown in  FIGS.  31 A- 31 B . The auxetic structures  3101  may include a plurality of interconnected members forming an array of reentrant shapes  3102 . The auxetic structures  3101  may be affixed to a base membrane or directly onto an outer shell. Such auxetic structures  3101  may be coupled or affixed to the shell protrusion as a continuous layer or in segmented arrays  3103 . The term “auxetic” generally refers to a material or structure that has a negative Poisson ratio, when stretched, auxetic materials or structures become thicker (as opposed to thinner) in a direction perpendicular to the applied force. Such auxetic structures can result in high energy absorption and/or fracture resistance. In particular, when a force is applied to the auxetic material or structure, the impact can cause it to expand (or contract) in one direction, resulting in associated expansion (or contraction) in a perpendicular direction. It should be recognized that those skilled in the art could utilize auxetic structures  3101  to include differently shaped segments or other structural members and different shaped voids. For example,  FIG.  31 B  illustrates an amplified view of one embodiment of an auxetic structure that is “bone” or “ribbon” shaped with radiused or arced re-entrant shapes. 
     In another embodiment, the impact mitigation layer may further comprise at least one foam layer or a portion of a foam layer. The at least one foam layer can include polymeric foams, quantum foam, polyethylene foam, polyurethane foam (foam rubber), XPS foam, polystyrene, phenolic, memory foam (traditional, open cell, or gel), impact absorbing foam (e.g., VN600),), Ethylene Vinyl Acetate foam (EVA), Ariaprene foam, latex rubber foam, convoluted foam (“egg create foam”), Evlon foam, impact hardening foam, 4.0 Custula comfort foam (open cell low density foam) and/or any combination thereof The at least one foam layer may have an open-cell structure or closed-cell structure. The at least one foam layer can be further tailored to obtain specific characteristics, such as anti-static, breathable, conductive, hydrophilic, high-tensile, high-tear, controlled elongation, and/or any combination thereof. For example,  FIGS.  47 A- 47 B  illustrates various views of a portion of a foam layer. The foam layer comprises a foam pad  4701 . The foam pad  4701  may be positioned on the crown of the wearer&#39;s head and conform to the curvature of the wearer&#39;s head. The portion of a foam layer may have a length  4704  and a height  4703 . The height  4703  may vary at a range between 0.5 inches to 2 inches. The length  4704  may vary from 2 inches to 6 inches. The foam pad  4702  may have a rectangular cross-section. The foam pad having a recess  4702  disposed on an external surface. 
     In another embodiment, the impact mitigation layer may further comprise at least one base layer. The at least one base layer may be a rigid and/or substantially rigid material. The at least one base layer may have a first surface and a second surface. At least a portion of an impact mitigation structure and/or a plurality of impact mitigation structures may be affixed to at least a portion of the at least one base layer first and/or second surface. Alternatively, at least one end of an impact mitigation structure and/or one end of a plurality of impact mitigation structures may be affixed to the at least one base layer first and/or second surface. Desirably, the at least one base layer may comprise two base layers, which the impact mitigation structure is disposed in between the two base layers. 
       FIGS.  32 A- 32 C  depict cross-sectional views of impact mitigation pads. In another embodiment, the impact mitigation layer may further comprise impact mitigation pads  3201 ,  3204 ,  3205 . The one or more impact mitigation pads  3201 ,  3204 ,  3205  may comprise a first material layer  3202 , a second material layer  3203 , and an impact mitigation structure  3204 . The first material layer  3202  and/or the second material layer  3203  may comprise a 2-way stretch material, a 4-way stretch material, and/or a foam layer. Additionally, the first material layer  3202  and/or the second material layer  3203  may further comprise a polymeric material, such as polypropylene, polyethylene, polyester, nylon, PVC, PTFE, and/or any combination thereof It also may be desirable to have a plurality of individual impact mitigation pads. Furthermore, the first material  3202  and/or the second material layer  3203  may be breathable and wick away moisture easily from the skin while carrying out various sporting and athletic activities. For example, the covering may completely or continually cover an entire array of impact mitigating structures (not shown). Conversely, the covering may cover at least a portion of an entire array of impact mitigating structures. Furthermore, the covering may cover segmented arrays of impact mitigating structures or individual impact mitigating structures (not shown). 
     In one embodiment, the impact mitigating structures can comprise a least a portion of liner pod assemblies as shown in  FIGS.  33 A- 33 D,  34 A- 34 B, and  35 A- 35 B .  FIGS.  33 A- 33 D  depict various views of one embodiment of an impact mitigation pod assembly  3301 . The one or more liner pod assemblies  3305  may include at least one individual pod (known as “pods” or “modular pods”) and/or a connecting mechanism that is coupled to a base membrane layer  3306  and/or inner shell or inner layer  3303 . If the one or more liner pod assemblies  3305  are assembled onto a base membrane layer  3306 , they will be coupled to the base membrane  3306  in a flat configuration then flexed or bend to create a shape that conforms to a wearers head. The base membrane  3306  may be manufactured with a polymeric or foam material. The polymeric or foam material may be flexible and/or elastic to allows it to be easily bent, twisted or flexed to conform to complex surfaces. Alternatively, the polymeric and/or foam material may be substantially rigid to provide a force distribution layer. The base membrane  3306  may comprise tabs  3302  that will be bent around the inner shell  3303  to couple the base membrane  3306  to the inner shell  3303 . The one or more pod assemblies  3305  can be modular and removably coupled into any configuration within the helmet. Each of the one or more pod assemblies  3305  may be positioned proximate to an adjacent to the one or more pod assemblies  3305 , such that the perimeter of each of the one or more pod assemblies  3305  may be parallel  3307  to the adjacent one or more pod assemblies  3305 . 
     Furthermore, additional spaces  3308  may not be covered in case the wearer desires further attachment of additional one or more pod assemblies  3305  and allow easier flexing capabilities. Each of the liner pod assemblies  3305  may include easily removable connections (or removably connected) to couple to the helmet (e.g., first or second shells), the impact mitigation layer and/or various components thereof. Each of the one or more liner pod assemblies may be manufactured to accommodate and protect the desired region of the wearer&#39;s head. Such plurality of liner pod assemblies  3305  may include regions such as one or more of the following: a frontal assembly (or front), an occipital assembly (or lower-back), a mid-back assembly (right and/or left sides), a parietal assembly (or midline), and a temporal assembly (right and/or left sides), and/or any combination(s) thereof. Alternatively, each of the one or more liner pod assemblies  3305  may be positioned adjacent to another liner pod assembly and connected by a flexible coupling to create a single-piece pod layer. The single-piece pod layer can be folded and manipulated to conform to the curvature of the head. 
     Alternatively, the one or more pod assemblies  3403  may be coupled directly to the inner shell  3402 . Each of the one or more liner pod assemblies  3403  may be manufactured to accommodate and protect the desired region of the wearer&#39;s head. Such plurality of liner pod assemblies  3403  may include regions such as one or more of the following: a frontal assembly (or front), an occipital assembly (or lower-back), a mid-back assembly (right and/or left sides), a parietal assembly (or midline), and a temporal assembly (right and/or left sides), and/or any combination(s) thereof. 
       FIGS.  35 A- 35 B  depict two alternative embodiments of a pod assemblies  3501 ,  3502 . Each of pods assemblies  3501 ,  3502  comprise a pod body  3503  and a connection mechanism  3504 . The pod body can comprise a generally triangular shaped body with rounded corners (an isosceles triangle, for example), although a variety of other shapes, including other shaped triangles, squares, pentagons, hexagons, septagons and/or octagon shapes, could be utilized in a variety of embodiments. In a similar manner, alternative shapes having rounded and/or sharp corners and/or edges may be utilized, as well as irregular and/or re-entrant shaped bodies, if desired. 
     In one exemplary embodiment, one or more liner pod assemblies can be provided in a series of sizes and/or thicknesses, such as the pods shown in  FIG.  35 A- 35 B , which depicts pods bodies of similar sizes but with varying thicknesses, from a first pod body having a ¼″ thickness progressively up to a fourth pod body with 1″ or 1.25″ or greater thickness. Desirably, the different thickness triangular pods bodies can be provided with similar external dimensions (i.e., height and/or width), with only the thickness differing to any substantial degree, allowing different thickness pods to be “mixed and matched” for use with a single helmet liner or other component, and/or other item of protective clothing. 
     The one or more liner assemblies may comprise at least one single foam layer construction. The connection mechanism  3504  is removably coupled or permanently coupled to the single foam layer pod. The single foam layer pod construction may further comprise one or more impact mitigation structures (not shown). The at least one foam layer can include polymeric foams, quantum foam, polyethylene foam, polyurethane foam (foam rubber), XPS foam, polystyrene, phenolic, memory foam (traditional, open cell, or gel), impact absorbing foam (e.g., VN600),), Ethylene Vinyl Acetate foam (EVA), Ariaprene foam, latex rubber foam, convoluted foam (“egg create foam”), Evlon foam, impact hardening foam, 4.0 Custula comfort foam (open cell low density foam) and/or any combination thereof The at least one foam layer may have an open-cell structure or closed-cell structure. The at least one foam layer can be further tailored to obtain specific characteristics, such as anti-static, breathable, conductive, hydrophilic, high-tensile, high-tear, controlled elongation, and/or any combination thereof 
     Alternatively, the one or more liner pods may comprise a multi-foam layer construction. the multilayer layer construction may include a single foam layer, an enclosure, and impact mitigation structure, and/or a second foam layer. Such multi-construction layers may allow the assembly to function as impact mitigation and comfort, thus, eliminating the need for an additional comfort liner. In another embodiment, the one or more liner pod assemblies may comprise a multi-layered pod construction and a connection mechanism. The multi-layered pod construction comprises two or more material layers. The two or more material layers may include at least one foam layer, a resilient and/or flexible fabric (e.g., a two-way or four-way stretch fabric) layer, a plastic layer (e.g., polycarbonate), and/or any combination thereof. More specifically, the multi-layered pod construction comprises a top layer, a first foam layer, a second foam layer, a bottom layer, and/or any combination thereof. Furthermore, the one or more liner pod assembly may further comprise an impact mitigation structure (not shown) or an impact distribution plate (not shown), and/or an impact mitigation structure and an impact distribution plate, where the impact mitigation structure and/or the impact distribution plate are disposed between the top layer and/or bottom layer. Each of the two or more layers may be different material layers and/or the same material layers. The at least one top layer and at least one bottom layer may be the same material, or they may be different materials. The at least one foam layer may be a one single layer, and/or it may be a plurality of foam layers (two or more). 
     Desirably, the one or more liner pod assemblies may be easily removable and interchangeable. For example, in order to increase the amount of protection on the left and/or right side of the helmet, the wearer may simply replace one or more of the liner pods on the right side of the helmet with thicker or thinner liner pod assemblies to balance the width reduction, and ultimately have proper helmet adjustment to accommodate the exchange of liner pod assemblies. Alternatively, the player may choose an “oversized” comfort liner which may be slightly “too big” for the wearer, and then the wearer can replace the liner pod assemblies in one or more regions with thinner liner pod assemblies to “fit” the helmet more appropriately. 
       FIGS.  36 A- 36 C  depict various views of one embodiment of a connection mechanism  3602 . The connection mechanism  3601  having a central body  3602 , and at least one longitudinal extending member  3603 . Each of the longitudinal extending members  3603  may be positioned symmetrically or asymmetrically around the perimeter of the central body  3602 . Each of the longitudinal extending members  3603  extends parallel from a surface of the central body  3602 . Each of the central bodies  3602  may comprise at least one fin  3603 , that may be positioned around the perimeter of the central body  3602  either symmetrically or asymmetrically. The fins  3603  are sized and configured to fit within one or more cavities on the base membrane layer and/or the inner shell. 
     Inner Shell 
     In one embodiment, the adjustable helmet assembly may further comprise at least one inner shell, the inner shell being a force distribution layer. The inner shell being nested within the impact mitigation layer. The inner shell having an exterior surface and an interior surface. The at least one inner shell being a continuous shell that conforms and surrounds the head of the wearer. Alternatively, the at least one inner shell may have a two or more portions that align with the adjustable helmet system. 
     Accordingly, the at least one inner shell may be a rigid material. The at least one inner shell may be more rigid than the adjustable helmet system and/or more rigid than the impact mitigation layer. In some embodiments, the inner shell is five to 100 times stiffer or more rigid than the adjustable helmet system and/or the impact mitigation layer. The rigid material may comprise polycarbonate (PC). Alternatively, the inner shell comprises a relatively rigid material or relatively stiff material. The relatively rigid material may be stiff or rigid enough to withstand breakage or cracking, but flexible enough to deform slightly and distribute incident forces after an impact. The at least one inner shell may comprise a thermoplastic material. The thermoplastic materials may comprise polyurethane, polycarbonate, polypropylene, polyether block amide, and/or any combinations thereof 
     Supplemental Layers 
     In another embodiment, the adjustable helmet assembly may further comprise one or more supplemental layers. The adjustable helmet system includes a front shell, a back shell, a locking mechanism, and/or one or more supplemental layers. The helmet may further comprise an impact mitigation layer. The helmet may comprise a front shell (or first shell) and a back shell (or second shell), the first or second shell having an external surface and an internal surface. The locking mechanism being movable between a first unlocked position which allows the first and second shells to slide relative to each other and a second locked position which inhibits the first and second shells from sliding relative to each other. It may be desirous to supplement the impact mitigation layer with a one or more supplemental layers, and one or more supplemental layers may be positioned proximate to the impact mitigation layer and/or the supplemental layer may be positioned proximate to the front (or first) or back (or second) shells. In addition, the supplemental layer may be removably connected or coupled to the helmet and/or the impact mitigation layer for additional impact protection, comfort and fit for a user. The one or more supplemental layers may comprise one or more of the following: at least one foam layer, one or more liner pod assemblies, a one-piece pad assembly, a multi-piece pad construction, a polycarbonate layer and/or any combination thereof. 
     The supplemental layer may comprise of one or more liner pod assemblies as disclosed herein. The liner pod assemblies may be used as either a mitigation structure, supplemental layer and/or a combination thereof The one or more liner pod assemblies may be positioned proximate to the mitigation structure and/or positioned proximate to the front and or back shells. Alternatively, the one or more liner pod assemblies may be coupled to the helmet, the impact mitigation layer, or both the helmet and the impact mitigation layer. Furthermore, the one or more liner pod assemblies may be coupled to a polycarbonate layer or a rigid polymer layer. 
     The one-piece supplemental layer may comprise a plurality of segmented pads that are coupled to the adjacent pad through a pivotal or flexible, elastic connection. Each of the plurality of pads may comprise a first layer, a second layer, and at least one foam layer. Each of the plurality of segmented pads are separated by gap. The foam layer is disposed between the first and second layer. The gap has a thickness, the thickness allowing substantial flexibility and/or a pivotal connection. Each of the plurality of pads may be placed in specific regions within the helmet, such as at least one frontal region (or front), an occipital region (or lower-back), a mid-back region, a parietal region (or midline), and a temporal region (right and/or left sides), and/or any combination(s) thereof The first or second layer may comprise a two-way stretch fabric, four-way stretch fabric, Neoprene, Ducksan Power Net, thermoplastic polyurethane (TPU), any wicking material, any antimicrobial material, polycarbonate material and/or any combination thereof. 
     The at least one foam layer can include polymeric foams, quantum foam, polyethylene foam, polyurethane foam (foam rubber), XPS foam, polystyrene, phenolic, memory foam (traditional, open cell, or gel), impact absorbing foam (e.g., VN600), Ethylene Vinyl Acetate foam (EVA), Ariaprene foam, latex rubber foam, convoluted foam (“egg create foam”), Evlon foam, impact hardening foam, 4.0 Custula comfort foam (open cell low density foam) and/or any combination thereof The at least one foam layer may have an open-cell structure or closed-cell structure. The at least one foam layer can be further tailored to obtain specific characteristics, such as anti-static, breathable, conductive, hydrophilic, high-tensile, high-tear, controlled elongation, and/or any combination thereof The at least one foam layer may comprise of segmented pieces and/or one continuous layer. 
     Alternatively, the supplemental layer may comprise a plurality of individual segmented pads providing for a multi-piece construction. Each of the plurality of individual pads may comprise a first layer, a second layer, and at least one foam layer. The foam layer is disposed between the first and second layer. Each of the plurality of individual pads may be placed in specific regions within the helmet, such as at least one frontal region (or front), an occipital region (or lower-back), a mid-back region, a parietal region (or midline), and a temporal region (right and/or left sides), and/or any combination(s) thereof The first or second layer may comprise a two-way stretch fabric, four-way stretch fabric, Neoprene, Ducksan Power Net, thermoplastic polyurethane (TPU), any wicking material, any antimicrobial material, polycarbonate material and/or any combination thereof. 
     In another embodiment, the supplemental layer  4601  may comprise a plurality of segmented assemblies  4603  providing for a multi-piece construction as shown in  FIGS.  46 A- 46 B . Each of the segmented assemblies  4603  comprise one or more liner pod assemblies  4604  as disclosed in  FIGS.  35 A- 35 D , and/or one or more individual pads as disclosed in  FIG.  32 A- 32 C , each of the one or more liner pod assemblies  4604  and/or each the one or more individual pads coupled to a base layer  4605 . The base layer  4605  may be a polymer, the polymer may be relatively rigid or a rigid material. Each of the plurality segmented assemblies  4603  may be placed in specific regions within the helmet, such as at least one frontal region (or front), an occipital region (or lower-back), a mid-back region, a parietal region (or midline), and a temporal region (right and/or left sides), and/or any combination(s) thereof 
     Example Embodiments 
     1. An adjustable helmet comprising: 
     A first shell; 
     A second shell, the second shell being slidably attached to the first shell, 
     A locking mechanism, the locking mechanism being movable between a first unlocked position which allows the first and second shells to slide relative to each other and a second locked position which inhibits the first and second shells from sliding relative to each other. 
     2. An adjustable helmet comprising: 
     A first shell; 
     A second shell, the second shell being slidably attached to the first shell; 
     A locking mechanism, the locking mechanism being movable between an unlocked position which allows the first and second shells to slide relative to each other and a locked position which prohibits the first and second shells from sliding relative to each other. 
     At least one opening, the at least one opening placed adjacent to, in proximity to or within impact zones of the first or second shells, thereby absorbing the energy from an impact and reducing the transfer of the impact force to an adjacent portion of the first or second shell and/or to the wearer&#39;s head. 
     3. The adjustable helmet of claim  2 , wherein the impact zones are located within the occipital region, temporal region, parietal region, orbit region, the frontal region, the mandible (front, right and/or left side) region, the maxilla region, the nasal region, zygomatic region, the ethmoid region, the lacrimal region, the sphenoid region and/or any combination thereof 
     4. The adjustable helmet of claim  2 , wherein the flexure and/or local deformation may occur laterally, perpendicular, oblique, normal to helmet plane, tangent to helmet plane, perpendicular to helmet plane, or parallel to helmet plane, and/or any combination thereof 
     5. The adjustable helmet of claim  2 , the at least one opening may be positioned in plane tangent to the helmet circumference, in a plane perpendicular or substantially perpendicular to the helmet plane, or in an oblique plane to the helmet plane, in a plane parallel to helmet plane, and/or any combination thereof. 
     6. An adjustable helmet comprising: 
     A first shell; 
     A second shell, the second shell being slidably attached to the first shell; and 
     A locking mechanism, the locking mechanism including: 
     a clamp assembly, 
     a plurality of teeth, at least a portion of the plurality of teeth sized and configured to fit within a portion of a plurality of recesses, the plurality of teeth disposed on the first or second shell, 
     a plurality of recesses, at least a portion of the plurality of recesses are sized and configured to receive the plurality of teeth, the plurality of recesses disposed on the first or second shell, the clamp assembly being movable between an unlocked position that allows the plurality of teeth and the plurality of recesses to disengage and allows the first and second shells to slide relative to each other, and a locked position that allows the a portion of the plurality of teeth and a portion of the plurality of recesses to engage and inhibits the first and second shells from sliding relative to each other. 
     7. An adjustable helmet comprising: 
     A first shell; 
     A second shell, the second shell being slidably attached to the first shell; and 
     A locking mechanism, the locking mechanism including: 
     a clamp tongue, clamp tongue extending away from the first or second shell, the clamp tongue having a plurality recesses, at least a portion of the plurality of recesses are sized and configured to receive a portion of a plurality of teeth, 
     a plurality of teeth, at least a portion of the plurality of teeth sized and configured to fit within a portion of the plurality of recesses, the plurality of teeth disposed on a portion of the first or second shell, 
     a clamp assembly, the clamp assembly being movable between an unlocked position that disengages the portion of the plurality of teeth from the portion of the plurality of recesses and allows the first and second shells to slide relative to each other, and a locked position that allows a portion of the plurality of teeth and a portion of the plurality of recesses to engage and inhibits the first and second shells from sliding relative to each other. 
     8. An adjustable helmet comprising: 
     A first shell, the first shell having an external surface and an internal surface; 
     A second shell, the second shell being slidably attached to the first shell, the second shell having an external surface and an internal surface; and 
     A locking mechanism, the locking mechanism including: 
     a clamp tongue, clamp tongue extending away from the first or second shell, the clamp tongue having a plurality of recesses, at least a portion of the plurality of recesses are sized and configured to receive a portion of a plurality of teeth, 
     a plurality of teeth, at least a portion of the plurality of teeth sized and configured to fit within a portion of the plurality of recesses, the plurality of teeth disposed on a portion of the first or second shell, 
     a clamp assembly, the clamp assembly being movable between an unlocked position that disengages the portion of the plurality of teeth from the portion of the plurality of recesses and allows the first and second shells to slide relative to each other, and a locked position that allows the a portion of the plurality of teeth and a portion of the plurality of recesses to engage and inhibits the first and second shells from sliding relative to each other. 
     a cavity, the cavity being sized and configured to receive the clamp assembly, the cavity being disposed within the first or second shells, the clamp assembly having a top surface and a bottom surface, the clamp assembly top surface being flush or substantially flush with the external surface of the first or second shell. 
     9. An adjustable helmet comprising: 
     A first shell, the first shell having an external surface and an internal surface; 
     A second shell, the second shell being slidably attached to the first shell, the second shell an external surface and an internal surface; and 
     A locking mechanism, the locking mechanism including; and 
     a clamp assembly, the clamp assembly having a clamp body, the clamp post, and a base plate; 
     a clamp tongue, clamp tongue extending away from the first or second shell, the clamp tongue having a top surface, a bottom surface and a first channel, the clamp tongue top surface having a plurality of a plurality recesses, at least a portion of the plurality of recesses are sized and configured to receive a portion of a plurality of teeth, the channel sized and configured to receive the clamp post; 
     a plurality of teeth, the plurality of teeth disposed on a portion of the first or second shell internal surface, at least a portion of the plurality of teeth sized and configured to fit within a portion of the plurality of recesses, the first or second shell internal surface further including a second channel, the second channel sized and configured to receive the clamp post; 
     a cavity, the cavity being sized and configured to receive the clamp assembly, the cavity being disposed within the first or second shells external surface, the clamp assembly having a top surface and a bottom surface, the clamp assembly top surface being flush or substantially flush with the external surface of the first or second shell, the cavity having an aperture, the aperture sized and configured to receive the clamp post; the base plate coupled to the clamp post, the base plate abuts the bottom surface of the clamp tongue; 
     a clamp assembly, the clamp assembly being movable between a locked position and an unlocked position, the locked position places tension on the clamp post and the base plate to compress the clamp tongue allowing a portion of the plurality of teeth and a portion of the plurality of recesses on the clamp tongue to engage and inhibit the first and second shells from sliding relative to each other, the unlocked position places compression on the clamp post and the base plate to release the clamp tongue allowing the portion of the plurality of teeth and the portion of the plurality of recesses of the clamp tongue to disengage, and allow the first and second shells to slide relative to each other. 
     10. The adjustable helmet of claim  1 ,  2 ,  5 ,  6 ,  7  or  8 , wherein the adjustable helmet further comprises an impact mitigation layer. 
     11. The adjustable helmet of claim  1 ,  2 ,  5 ,  6 ,  7  or  8 , wherein the adjustable helmet further comprises a supplemental layer. 
     12. The adjustable helmet of claim  1 ,  2 ,  5 ,  6 , Tor  8 , wherein the adjustable helmet further comprises ear protection. 
     13. The adjustable helmet of claim  1 ,  2 ,  5 ,  6 ,  7  or  8 , wherein the adjustable helmet further comprises a jaw frame. 
     14. The adjustable helmet of claim  1 ,  2 ,  5 ,  6 ,  7  or  8 , wherein the adjustable helmet further comprises a chin strap. 
     15. The adjustable helmet of claim  10 , wherein the supplemental layer is one or more liner pod assemblies. 
     16. The adjustable helmet of claim  14 , wherein the one or more liner pod assemblies are removably connected. 
     17. An improved helmet, comprising: 
     a helmet, the helmet having an outer layer and a shell protrusion, the outer layer having an outer surface and an inner surface, the shell protrusion extending outwardly from the outer layer outer surface, and 
     at least one impact mitigation feature, the at least one impact mitigation feature being disposed onto the shell protrusion and extending therethrough; 
     18. An improved helmet, comprising: 
     a helmet, the helmet having an outer layer and a shell protrusion, the outer layer having an outer surface and an inner surface, the shell protrusion extending outwardly from the outer layer outer surface, and 
     at least one impact mitigation structure, the at least one impact mitigation structure being disposed onto the shell protrusion; 
     19. An improved helmet, comprising: 
     a helmet, the helmet having an outer layer and a shell protrusion, the outer layer having an outer surface and an inner surface, the shell protrusion extending outwardly from the outer layer outer surface, the shell protrusion having a cavity disposed within, and 
     at least one impact mitigation structure, the at least one impact mitigation structure being disposed within the cavity of the shell protrusion; 
     20. An improved helmet, comprising: 
     a helmet, the helmet having an outer layer and a shell protrusion, the outer layer having an outer surface and an inner surface, the shell protrusion extending outwardly from the outer layer outer surface, the shell protrusion having a cavity disposed within, and 
     at least one impact mitigation structure, the at least one impact mitigation structure replacing the shell protrusion.