The Giro(R) Adult Quarter(TM) Bike Helmet is extremely lightweight and is designed to give you full coverage and protection when you venture out on the dirt trails or practicing on dirt jumps. Designed with a Super Fit(TM) sizing system and Fit Kit(TM) Pad system, you can quickly adjust the sizing of the helmet up to 4 sizes and the amount of padding for a comfortable and snug fit. FEATURES: Low profile design Suggested for bmx biking and dirt trails Super Fit(TM) sizing system adjusts up to 4 sizes for a close and comfortable fit Ventilation: 8 vents Tough ABS Shell with impact absorbing EPS Liner Polyurethane coating helps protect EPS liner Fit Kit(TM) Pad system allows you to change the placement and amount of padding in the helmet Features soft sweat absorbent pads to keep you dry Complies with U.S. CPSC Safety Standard for Bicycle Helmets for persons age 5 and older Style: 7055601 Sizing: S: 20"-21.75"/ 51-55 cm M: 21.75"-23.25"/ 55-59 cm L: 23.25"-24.75"/ 59-63cm