Made from 17-4 Stainless Steel and is heat treated then black nitride finished for improved wear and corrosion resistance. Our pistons come with wrench flats that allow for a more secure attachment to your firearm. – Features – Interchangeable with SilencerCo and Rugged pistons – Interchangeable between RAD 9 & 45 – Pair with a Piston Spring for reciprocating barrels or Fixed Barrel Spacer for fixed barrels. – Wrench flats