This AAC Blackout Muzzle Brake is a highly efficient and effective brake designed to significantly reduce recoil and help keep shooters on target for faster shot-to-shot recovery. All Blackout muzzle brakes are machined from high strength aerospace 17-4 stainless steel alloy and coated in a hard, durable, corrosion resistant SCARmor finish. This 51T Blackout muzzle brake works in conjunction with AAC's improved ratchet mount sound suppressors. The 51-T mount is an intuitive, lightning fast silencer attachment/detachment system that allows for secure installation of a suppressor in less than 3 seconds with no tools or moving parts. Not compatible with the older spring mount (18-Tooth) or newer ratchet taper mount (90-Tooth) sound suppressors. Torque wrench is need for installation - approximately 20-30ft.-lbs.