(R)ecoil (R)eduction (D)evice (4) ports (C)ompensator (1/2x28) thread pitch (F)ace - sits on the face of the barrel (KM) KeyMount This is designed to be permanently attached to a 14.5 inch barrel and adapt to KeyMo compatilble suppressors! We recommend this muzzle device be professionally installed on our 14.5" barrel by one of our Kalashnismiths to ensure alignment. BARREL DIAMETER MUST BE <0.585" This WILL NOT work on a standard AKM, pistol, or SBR. Barrel must extend at least 1.32" from the gasblock Features: 1/2-28 threads 2.82" long Only adds 1.5" Sleeves the barrel 1.32" 17-4ph Stainless 3.6oz This device is designed to be tightened against the face of the barrel. Your barrel MUST be faced to properly time this muzzle device.