The LS2 Thunder Carbon Helmet A high performance full-face motorcycle helmet designed for the world's most demanding racetracks. Shell The lightweight, aerodynamic Pure Carbon Fiber shell slices through the wind and remains stable on your head. Sizes range from X-Small to 2X-Large. 3 shell sizes for a perfect fit! Meets or exceeds DOT FMVSS 218, ECE 22.06, and FIM FRHPhe-01. The Thunder Carbon is one of few helmets to earn the FIM FRHPhe-01 standard on a retail helmet! Look on the chinstrap for the holographic logo! Shield The optically correct shield swaps quickly and easily using tool-less quick release technology. This race-ready 3mm flat shield comes with tear-off posts and uses the Pinlock system for the ultimate in fog resistance. Security The Thunder uses a traditional “Double-D Ring” strap for a secure fit. The fit is snug, but comfortable for those long endurance races or high speed jaunts, we call it the 200 M.P.H. fit. Ventilation The fully adjustable, multiport, dynamic, flow through ventilation with channeled EPS to keep you cool. Shell Shield Security Ventilation Colorways Thunder Carbon Helmet Thunder Carbon in colorway Carbon Fiber Thunder Carbon Alliance Helmet Thunder Carbon Alliance Helmet in colorway Gloss Red/White/Blue Thunder Carbon Lightning Helmet Thunder Carbon Lightning Helmet in colorway Gloss Red/White/Black Important Sizing Note Begin by measuring the circumference of your head with a tape measure or a lengthy string that you can line up with a ruler. Start above the ear and circle around completely, resting right at the center of the eyebrows and at the fullest part in back. Measure multiple times to ensure you don't measure to small or large. Important Sizing Note Begin by measuring the circumference of your head with a tape measure or a lengthy string that you can line up with a ruler. Start above the ear and circle around completely, resting right at the center of the eyebrows and at the fullest part in back. Measure multiple times to ensure you don't measure to small or large.