Giro Selector Road/Race Bike Helmet Set and forget Roc Loc TT Fit system creates a self-adjusting fit with secure feel and helps improve aerodynamics by allowing back of the helmet to be closed off to the wind In-mold polycarbonate shell with EPS liner Internal channeling ventilation and X-Static padding Featherweight webbing with Slimline buckle 10mm "Shallow" tail for riders with flatter back profile and 45mm "Tall" tail for riders with compact/hunched back profile