Giro Section Bike/Multi-Sport Helmet Skate-style, multi-sport helmet for urban commuting, dirt jumping, and trail-riding In-mold construction fuses a tough polycarbonate outer shell with the helmets impact-absorbing foam liner Wind Tunnel ventilation system combines active vents with internal exhaust channels that thrust cool, fresh air over your head Three-size Super Fit system for a fit that feels like it was custom made just for you Ultra-light helmet; open cell foam padding In-mold hardbody with full coverage shell.51 - 55cm / 20 - 21.75-Inch Ultra-light at only 296 grams, size Medium (compared to 445 grams  Flak, size Medium). 8 vents and understated Giro metal badge branding Open cell foam padding