Bravo Company's BCM KMR ALPHA 7"""" KeyMod Free Float Handguard"" is manufactured from aluminum"" it is lightweight yet durable. Also featuring a proprietary patent pending mounting"" indexing and lock up system that mitigates 12:00 rail movement under heat generated from the barrel nut. It has a 1.3"" inner diameter and is 1.5"" outside flat to flat. The handguard flares forward (towards muzzle end) at the 3 and 9 O'clock positions approximately 1/4"". The actual length when measured to flare is 7.39"". The KeyMod(TM) interface system was developed by Eric Kincel (now the Director of BCMs' product development team) to work in parallel with the current picatinny system. In many applications it will advance modularity past the current 1913 rail system. In the most basic of applications the KeyMod(TM) system allows for universal modularity between various manufacturers of accessories"" and accessory rails. A big win for the trigger puller. As the industry advances the modular accessories will mount directly to the KeyMod(TM) instead of picatinny"" allowing for a lighter"" cleaner"" and less bulky weapon system. Fits AR rifles. Includes BCM(R) KeyMod(TM) Sling Mount.