The Quarter is one of the lowest-profile helmets Giro have ever made, and it\\\'s also the lightest we\\\'ve made with an ABS shell. The essentials are here - an EPS liner for impact management, a tough outer shell, riveted webbing anchors and plush, sweat-absorbent pads for long-lasting comfort. Another standout feature - the Roc Loc Vert dial fit system allows you to easily adjust the helmet for a secure and stable fit. Key Features ABS shell with EPS liner Roc Loc Vert dial fit system for easy head size fit 8 vents for optimum ventilation Giro Helmet SizingSMLXLHead Circumference (CM)51-55cm55-59cm59-63cm61-65cm Helmets Buying Guide