Outer Shell Construction:In-mold polycarbonate shell with EPS liner. Inner Shell:Thermoformed reinforcement shock absorbing polystyrene. Lightweight fit system with an easy-to-turn dial for adjustments. 15 Wind Tunnel vents with internal channeling. Removable and washable inner padding in Coolmax material- COOLMAX internal pads are used in larger surface in contact with the head for increased comfort. Detachable for hand wash and anti-allergenic.Comfort Liner and Chin Pading keeps a good fit.