Giro Eclipse Pro Spherical II Helmet Engineered to win Tour de France breakaways and Leadville Trail 100 victories share one thing in common - the Giro Eclipse Pro. Built in deep collaboration with the world's fastest pros and endlessly refined through CFD analysis and wind tunnel testing, the Eclipse Pro is 17% faster than the legendary Eclipse that came before it. At just 280g it rivals the lightest fully-vented climbing helmets on the market, yet packs in Spherical Technology powered by Mips(R), 15 Wind Tunnel vents, the Aura II Reinforcing Arch, and the Dry Core(TM) sweat management system. This is what purpose-built looks like. Features Spherical Technology powered by Mips(R) uses a ball-and-socket design to redirect rotational impact forces away from the brain, while eliminating contact with hard plastic or slip-planes against the skin17% faster than the previous Eclipse - developed using CFD and validated in the wind tunnel with the world's fastest pros15 Wind Tunnel vents with deep internal channeling push cool air over and around the rider's head while forcing heat and stale air out Front center vent splits air to the forehead and over the brow for aerodynamic efficiency Aura II Reinforcing Arch - a shatter-resistant, translucent arch that runs throughout the helmet, bolstering structural integrity while enabling massive vent openings Dry Core(TM) sweat management system uses an internal silicone bead to redirect moisture away from the brow and keep sweat out of the eyes Progressive Layering(TM) dual-density EPS foam liners manage both high- and low-speed impacts for more comprehensive energy absorption Roc Loc(R) 5. 5 Air Fit System suspends the helmet slightly off the skull for direct airflow over the head, with one-handed micro-adjustment of fit tension and fore-aft tilt IONIC+(R) padding uses pure silver for permanent, natural odor protection Ultra-lightweight at 280g (size M, CPSC) - lighter than many fully-vented road helmets SPECIFICATIONSWeight280g (Size M, CPSC)Fit System Roc Loc(R) 5. 5 Air Vents15MIPSSpherical Technology powered by Mips(R)Intended Use Road, Road Race Sizing Size Small Medium Large XLHead Circumference (in)20. 1 - 21. 7"21. 7 - 23. 2"23. 2 - 24. 8"24. 8 - 25. 6"Head Circumference (cm)51 - 55cm55 - 59cm59 - 63cm63 - 65cm | Giro | Eclipse Pro Spherical Ii Helmet Men's | Size Small In Matte Black