IRH Air-Lite DFS Helmet The Air-Lite DFS helmet is a lightweight helmet, only 11 ounces, with a classic design that gives you a traditional style and is well ventilated. These features make this helmet perfect for all disciplines and for competitive levels. It also includes fully adjustable side straps and a low profile rear cut to accept a pony tail. F1163.04a/USA/SEI Certified/EN-1384/CE Mark Europe. Features: Dial-Fit system 3-Point Harness Front ventilation Easy to clean outer SEI and ASTM certified 11 ounces Specifications: Sizes: Small (6 1/2, 6 5/8, 6 3/4) Medium (6 7/8, 7, 7 1/8) Large (7 1/4, 7 3/4, 7 1/2).