Triple Eight Lil 8 Certified Helmet Dual Certified: Complies with U.S. CPSC Bike and ASTM Skate safety standards ABS Outer Shell with EPS liner Complete with our renowned Sweatsaver Fit Pads for added comfort Adjustable Fit Dial System to create a custom fit Padded Chin Buckle Protector to prevent pinching To ensure a perfect fit, measure the circumference of your head starting in the middle of your forehead and match it with the size - 18  20.5 in (46  52 cm)