Evo-9™ PistonA single Evolution Series silencer can be used on a variety of host firearms with different barrel threads by quickly and easily swapping out the threaded A.S.A.P. piston in the rear of the silencer. We manufacture A.S.A.P. pistons to match the barrel threads of all popular factory threaded pistol barrels and many aftermarket barrels. All Evolution Series Pistons feature heat treated stainless steel construction, a matte bead blasted finish, and engraving to identify the thread diameter, pitch, and direction of rotation for installation (Left Hand threads or Right Hand threads).