NOTE :Please according to head circumference,Choose right sizeXS:Head circumference: 43 cm-54 cm /17′-21′ Head width :10 cm /4′ (Recommendation children)S:Head circumference:48cm -56cm/19′-22′ Head width:12 cm /4.7′ (Recommendation children /Kids)M:Head circumference:50 cm-60cm /19.6′-23.6′ Head width :15 cm /5.9′(Recommendation Youth /Teen )L:Head circumference:54cm-64cm /21′-25′ Head width:18 cm/ 7′(Recommendation Adult )SpecificationBrand :KuYou Material :Multi-impact ABS Shell +EPS foam Liner, CE:Euro CE EN1078, Size :XS /S /M/ L Color: Blue/ White Black/ Pink /Yellow /OrangeApplication: BMX,Skateboard,Skidding,Bicycle,Cycling and other outdoor sports.Features: Fully Adjustable Quick-Release Chin-Strap and spin dial (which is removable)Design to help reduce the risk injuryComfortable and Easy to wearDesigned for All Types of Skating, Skateboarding and Cycling.Extended Rear Coverage to Protect Against Backward Falls. 11 Vents Designed to Force Cool Air In and Warm Air Out. Strong Protective ABS Outer Shell. Lightweight, Energy Absorbing EPS Lining Includes Extra Interior Pads for Custom Fitting. Conforms Adjustable Safety Standard EN1078. Warranty Please do not hesitate to contact us if you are not satisfied for any reason. Our products are backed by 18 months Warranty.