Guard Dogs FAST ballistic helmet provided IAW NIJ tested Level 3a low profile protection. This helmet is compatible with communication systems, gas masks and helmet mounted night vision goggles. Our helmet has a fully adjustable five point harness with a leather chinstrap that holds a quick release buckle. Total weight is less than 3.7lbs. Sizes Medium: Head circumference 21.25-23.75". Large: Head circumference 22"-23.75". XL: Head circumference 22.45-24.4". NIJ Level 3a: Tested to stop 4 rounds of .44 Magnum SJHP traveling 1430 ft/s +/- 30ft/s Specifications for Guard Dog Body Armor Level IIIA FAST Ballistic Helmet: Manufacturer: Guard Dog Body Armor Threat Level: Level IIIA Features of Guard Dog Body Armor Level IIIA FAST Ballistic Helmet This helmet caters to a wide range of users with head circumferences ranging from 20.0 inches to 23.75 inches. Lightweight Design: Weighing in at less than 3.7 pounds, this helmet wont weigh you down during extended wear. Versatile Compatibility: Designed to accommodate communication systems, gas masks, and helmet-mounted night vision goggles, our helmet offers seamless integration with your essential gear. Fully Adjustable Five-Point Harness: Achieve a secure and comfortable fit with our easy-to-adjust harness, ensuring your helmet stays in place when you need it most. Premium Leather Chinstrap: Thier chinstrap, complete with a quick-release buckle, offers both durability and convenience, allowing for swift deployment. Package Contents: Guard Dog Body Armor Level IIIA FAST Ballistic Helmet Polymer Picatinny ARC Rail Adapter Green Camouflage Cloth Helmet Cover