Giro Helios Spherical Helmet Performance, anywhere. The Giro Helios Spherical helmet is Giro's high-performance adventure-ready helmet featuring their Spherical protection technology, perfect for your next backroads exploration session or competitive group ride. The Spherical ball-and-socket technology incorporated into the Helios provides protection from rotational forces during an impact, allowing the inner and outer layers to rotate separately to disperse harmful forces in the event of a crash. Progressive Layering allows for better absorption of energy from low and high speed impacts. The 15 vents on the Helios direct air into internal channels, providing excellent cooling during hard efforts, while IONIC+ antimicrobial padding with pure silver keeps the funk at bay. No matter the terrain, the Helios Spherical by Giro will take you there. Features Spherical Technology powered by MIPS ball-and-socket design allows the inner and outer helmet layers to rotate separately, absorbing rotational forces Roc Loc(R) 5 Air Fit System combines easy helmet retention with optimized airflow by suspending the helmet slightly above the rider's head IONIC+ antimicrobial padding with pure silver, keeps moisture away from the rider's eyes, while keeping the funk at bay15 Wind Tunnel vents direct airflow into internal channels for optimal cooling Progressive Layering of inner and outer shell layers provide better energy absorption for high and low speed impacts SPECIFICATIONSCore Material Nanobead EPS foam Closure system Buckle Intended Use Road, Gravel, Cyclocross Weight270 grams (size M)Sizing Size Extra Small Small Medium Large Extra Large Head Circumference (in)18. 5 - 20"20 - 21. 75"21. 75 - 23. 25"23. 25 - 24. 75"24 - 25. 55"Head Circumference (cm)47 - 51cm51 - 55cm55 - 59cm59 - 63cm61 - 65cm | Giro | Helios Spherical Gbl Helmet Men's | Size Medium/large In White