This Ruger Hybrid Muzzle Brake reduces recoil and muzzle rise, contributing to improved accuracy over a longer string of fire. It also reduces noise and debris by directing the blast to the sides of the shooter. The brake is timed using the A 1/2" crush washer (2 included) and installs quickly using a 7/8" box wrench or crescent wrench. Washers should be installed with the cupped side towards the muzzle. It is manufactured from 4140 chrome moly steel with a matte black finish. It fits rifles with A 1/2"-28 x .400 length threads chambered in .350 Legend including the AR-556 and the Ruger American Rifle Ranch and the PC Carbine chambered in 9mm. Genuine Ruger Factory Accessory.