Challenger II Viper Helmet. The Challenger II is a high-performance sport-touring helmet crafted from lightweight HPFC (High-Performance Fiberglass Composite). Engineered for superior aerodynamics and optimal ventilation, it delivers comfort and stability for both daily commutes and extended touring adventures. Shell: Meets or exceeds DOT FMVSS 218 and ECE 22.06. Weight: 1500 grams,±50 grams. Made using High Performance Fiberglass Composite (HPFC). Three shell sizes, five EPS sizes, seven Liner sizes, and three Cheek Pad set sizes. Comfort: The premium removable and washable COOLMAX® liner delivers exceptional moisture management, high breathability, and quick-drying performance. Its hypoallergenic and anti-odor properties help maintain long-lasting freshness. Shield: