From sunrise to sunset, the Radix designed by Giro is the ideal mountain bike helmet for riding comfortably on the most beautiful trails of Aravis or Mercantour, with complete confidence. The Roc Loc® system allows you to customize the fit and feel, for long-lasting comfort and better protection. The 25 ventilation channels ensure perfect airflow, even on the hottest summer days. Wrap-around In-Mold polycarbonate shell with EPS liner P.O.V visor Occipital retention: Roc Loc® Wind Tunnel vents with internal channels CoolFit anti-microbial padding 25 ventilation ducts Size: S: 51-55 - M: 55-59 Weight: 295 g Giro Radix - Mountain bike Helmet