Triple Eight Dual Certified Helmet, Large / X-Large Complies with US CPSC Safety Standard for Bike for ages 5+ and ASTM F-1492-08 Safety Standards for skateboarding and trick roller skating High-density ABS outer shell,Polystyrene Liner Triple Eight customized logo rivets Each Helmet comes standard with an extra set of fit pads to better customize fit To ensure a perfect fit, measure the circumference of your head starting in the middle of your forehead and match it with the sizes below: XS/S 18.9  21.3 in (48  54 cm) S/M 21.7  22.8 in (55  58 cm) L/XL 23.2  24 in (59  61 cm)