The Gamma 556SL is the perfect muzzle device for your pinned and welded builds. The Gamma 556SL is long enough to provide an overall length of 16" when permanently affixed to the barrel. Its outside diameter of .745 inches allows you to install and service your gas system without removing the muzzle brake. The 3-chamber design looks great on any standard profile barrel while effectively eliminating recoil leaving your rifle shooting flat and soft.