Mountain Road Bicycle Helmets Ultralight 18 Vents Cycling Helmet with Visor Vent qty: 18 vents Material: EPS & PC Head width: 19cm / 7.5in Head circumference: 54~64cm / 21.2~25.2in Item size: Approx. 27 * 21.5 * 15cm / 10.6 * 8.5 * 5.9in