Giro Feature Mountain Bike Helmet The evolution of coverage and performance for long-travel trail riding In Form Fit System In-mold polycarbonate shell construction with EPS liner 12 vents with internal channeling for superior ventilation Adjustable moto-style visor Sizes: S: 20"-21.75"/51-55cm, M: 21.75"-23.25"/55-59cm, L: 23.25"-24.75"/59-63cm