Giro Montane Snow Helmet Available in 3 Rock Loc Sizes: S(52-55.5cm), M(55.5-59cm), L(59-62.5cm) Super Light Weight (380g) In-Mold Construction 12 Super Cool vents with Thermostat Control plus Stack Ventilation Compatible with all after market TuneUps systems Compliance: ASTM F2040/CE EN1077