The Gentry Quiet Muzzle Brake reduces recoil up to 85% while directing gas and noise away from the shooter. The installation of a Quiet Muzzle Brake does not impact the firearm's velocity or accuracy. SPECS: Steel, PB (polished blue), MB (matte blue), or SS (stainless steel); satin finish. Length 1.94 inches (49.3 mm). Outer diameter 0.750 inches (19 mm). Threads: 1/2-28 TPI for all calibers, with 5/8-24 available for the 30 caliber variant.