wow youth kids motocross bmx mx atv dirt bike helmet shark red wow! ez finishes <b> helmet size chart</b> <br> <br> s 49-50 cm 19.3/19.7 inch <br> m 51-52 cm 20.1/20.5 inch <br> l 53-54 cm 20.9/21.3 inch <br> <b> helmet size tips</b> <br> <br>(1)wrap a measuring tape around your head about a half-inch above eyebrows <br>(2)take measurement two to three times to pick the largest one.