Race cycling helmet suitable for men sizes 51 55 cm 55 59 cm 59 63 cm us sizes s m l main colour grey number of air vents 26 inner padding antibacterial size adjustments wheel adjustment system strap adjustable construction in mold outer material polycarbonate weight 270 g inner material polystyrene eps helmet technologies giro roc loc 5 giro slimline webbing giro x static padding giro wind tunnel ventilation giro roll cage air channel venting