Race cycling helmet suitable for men sizes 53 57 cm 58 63 cm number of air vents 18 safety features fly net size adjustments wheel adjustment system headring features lower edge reinforcement construction in mold outer material polycarbonate weight 225 g inner material polystyrene eps helmet technologies alpina ceramic shell alpina hi eps alpina custom fit alpina run system alpina edge protect alpina ergomatic certified en din 1078