The BCM KMR Alpha 17 manufactured from aluminum, it is lightweight yet durable. Also featuring a proprietary mounting, indexing and lock up system that mitigates 12:00 rail movement under heat generated from the barrel nut. The KMR Alpha is hardcoat anodized for corrosion resistance as well as to maintain a non-reflective finish. In the most basic of applications the KeyMod system allows for universal modularity between various manufacturers of accessories and accessory rails. As the industry advances the modular accessories will mount directly to the KeyMod instead of picatinny, allowing for a lighter, cleaner and less bulky weapon system. Handguard alone weighs 9.9 oz, mounting hardware, 2.4oz, for a total of 12.3 oz. Handguard flares forward (towards muzzle end) at the 3 and 9 O'clock positions approximately 1/4", the barrel nut will fit over all mil-spec diameter barrels (max of 1"). Actual length when measured to flare is 17.00", 1.3" inner diameter and 1.5" outside flat to flat. Includes BCM KeyMod Sling Mount .