Triple Eight Invader Full Face Helmet Dual Certified: Complies with U.S. CPSC Bike and ASTM Downhill Mountain Bike Racing safety standards Durable Fiberglass Outer Shell with EPS liner Vented for great air flow; features an imposing Triple Eight Icon front vent Size Chart XS/S 20-21.75 in (51-55cm); S/M 21.75-23.25 in (55-59cm); L/XL 23.25-24.75 in (59-63cm)