Mountain bike helmet suitable for men sizes 51 55 cm 55 59 cm 59 63 cm 61 65 cm us sizes s m l xl main colours grey white number of air vents 21 applications all mountain touring visor with visor detachable adjustable 15 plug connection construction in mold outer material polycarbonate weight 310 g inner material polystyrene eps helmet technology air channel venting certified en din 1078