CY-Buity Road Mountain Bike Bicycle Cycling Sports Head Protect Helmets Crashworthiness, not brittle to withstand the high intensity, strong foam density. Use ONE STEP technical material, EPS increases impact resistance of composite materials. Ultra-light, wind tunnel, duct design, effectively reduces wind resistance. High-quality foam layer, the adjustment within the twist, you can adjust the size of head circumference. Suitable for:Head circumference: 65 cm Head width: 16 cm.