The helmet comes in extra-small, small, medium, large, extra-large, and extra-extra large sizes. Depending on size, it weighs approximately 19.5 ounces. An extra-small helmet fits a head with a circumference of 20.5 inches to 21 inches. A small helmet fits a head with a circumference of 21 inches to 22 inches. A medium helmet fits a head with a circumference of 22 inches to 22.5 inches. A large helmet fits a head with a circumference of 22.5 inches to 23.25 inches. An extra-large helmet fits a head with a circumference of 23.25 inches to 23.75 inches. An extra-extra-large helmet fits a head with a circumference of 23.75 inches to 24.5 inches.

About Giro
Working late nights in his garage, designer/bike racer Jim Gentes created the first lightweight adult cycling helmet in 1985. Friends at NASA helped tune the final helmet shape and vent placement, and the result was the Giro Prolight, a helmet that was better looking than traditional designs while offering a superior fit and still met the industry's toughest safety standards. Plus, it was half the weight of traditional helmets. Since then, Giro has advanced its helmets, many of which have set the standards for styling, function, and innovation for progressive, performance-oriented riders on dirt, pavement, and snow. Giro helmets are worn by millions of riders, cyclists, skiers, and snowboarders around the world. Young-bloods and old-timers; hard-cores, heshers, and hipsters; rookies, experts, and a few regular Joes too--in fact, pretty much anyone that appreciates superior fit and function, cutting edge styling, and the very best ideas you get in a helmet.