Giro Atmos II Road Bicycle Helmet. There's one thing world class road, cyclocross and XC mountain bike riders can agree upon that the Giro Atmos II Bicycle Helmet is the perfect choice for head protection when championships are on the line. The In Mold polycarbonate shell with EPS liner provides excellent impact protection and allows for bigger vents, all while remaining incredibly lightweight. Twenty six Wind Tunnel vents cool your entire head while the Roc Loc 5 retention system puts unrivaled fit and adjustability at your fingertips. To complete the high performance package, there's Slimline webbing and an ultra light buckle to shave precious grams.