With a combination of style, fit and comfort, the Bell Faction Downhill and BMX Bike Helmet features a skate-helmet-inspired design. This downhill and BMX-bike helmet is constructed of an ABS hard-plastic shell with a dual-density EPS liner, and includes 12 vents that allow cool, fresh air in and warm air out. The Faction helmet comes in three sizes: small (51-56cm), medium (54-59cm), and large (58-63cm). Bell"s Faction helmet weighs 425 grams, and is both CPSC bicycle safety-standard certified and ASTM 1492 skate certified.