Sportsrain Adult Ajustable Bike Helmet With Snap On/Off Visor In Black, Black And White Use One Step Technical Material, Eps Increases Impact Resistance Of Composite Materials Ultra-Light, Wind Tunnel, Duct Design, Effectively Reduce Wind Resistance. High-Quality Foam Layer, The Adjustment Within The Twist, You Can Adjust The Size Of Head Circumference. Suitable For People With Head Circumference 56-63Cm And The Head-Width Below 17.5Cm 18 Flow Vents To Keep You Cool With Snap On/Off Visor For Sun Protection