Kids helmet mountain bike helmet suitable for girls sizes 47 52 cm 52 57 cm us sizes s m main colours blue pink white purple number of air vents 17 safety features fly net visor with visor size adjustments wheel adjustment system headring construction in mold weight 220 g inner material polystyrene eps helmet technologies alpina ceramic shell alpina hi eps alpina run system alpina ergomatic theme flower certified en din 1078