If you ride everything and ride fast you need the same cool comfort and performance whether yoursquore on the open road or your favourite singletrack the giro fathom mtb helmet is a twin to the legendary atmos a breakthrough helmet design that offers amazing ventilation thanks to a clever internal reinforcement structure giro fathom mtb helmet features roc loc 5 fit system removable visor thermoformed sl reinforcement in mold polycarbonate shell with eps liner 23 wind tunnel ven