Triple 8 Helmet Certified Deep Cover Patent-Pending HIDDEN-HINGE Technology provides just the right amount of auto-flexing adjustment deep inside The Back Fit LUXE-LOCK Liners are a revelation with 3 densities of precision-shaped foam wrapped in sweat-wicking fabric to cradle the occipital region at the base of your skull. Once you experience it, there's no going back Advanced FIT KIT with 17 Liners and Shims for customization to your unique head shape Classic Shape, Deepest Fit, and Lowest Profile in 4 sizes each with unique ABS and EPS Shell for the closest fit to your head Complies with U.S. CPSC Safety Standard for Bicycle Helmets for Persons Age 5 and Older, ASTM F1447 Standard Specification for Helmets Used in Recreational Bicycling or Roller Skating, and ASTM F1492 Standard Specification for Helmets Used in Skateboarding and Trick Roller Skating.