HUXWRX PISTOL SUPPRESSOR PISTONS Made from 17-4 Stainless Steel and heat treated. HUXWRX pistons come with wrench flats that allow for a more secure attachment to your firearm. FEATURES: Interchangeable with SilencerCo and Rugged pistons Pair with a Piston Spring for reciprocating barrels or Fixed Barrel Spacer for fixed barrels. Mfg: Brownells