With Hardshell construction ready to take on whatever mischief more aggressive skaters get themselves into, and a 2-stage soft foam liner, it's no wonder there are so many Classic Skate wannabes out there. Look sleek and skate tough in the Pro-Tec Classic Skate Skateboard Helmet. Stainless Hardware 11 Open Vents HDPE Flex HDPE is made up of a foam-fitting, high-density polyethylene shell, with flexibility to fit a broader range of head shapes. HDPE shells accompany Pro Tec's 2-stage soft foam liners, not certified to ASTM, CPSC, or CE Safety Standards. 2-Stage Soft Foam Liner Low-profile and lightweight for a snug and comfortable fit. Doesn't meet certification standards for action sports helmets. Transition from soft to hard, away from your head, out toward the hard shell of the helmet.