Granvela Lightweight Cycle Helmet Mountain Bike Helmet Adjustable Thrasher 22-24 inch with 28 Vents - for Men/Women Materials: in-mold polycarbonate shell with EPS liner Ventilation: 28 vents allow cool air in and warm air out Adjustment: 22.05"-24.41" head circumference adjustable Weight: quality materials, 209 g ultra-light helmet Features: streamlined design, anti-windage, lightweight, strong, 28-hole breathable big holes, with visor, comfortable lining, and regulator.