Mountain bike helmet suitable for men sizes 51 54 cm 55 58 cm 59 62 cm us sizes xss ml xlxxl main colour green number of air vents 16 application all mountain visor with visor size adjustments headring strap adjustable features neck protection enhanced protection for back of head construction in mold outer material polycarbonate weight 340 g inner material polystyrene eps marks of approval en din 1078 cpsc