This silencer piston is made by Sig Sauer and is constructed out of heat-treated stainless steel. The addition of this piston allows the user to convert their .9mm SRD9 suppressor to a right handed 1/2x28 thread pitch. Installation is quick and easy, just replace the original piston with this conversion in your suppressor to match your barrel’s thread pattern. Disclaimer: All NFA rules apply Sig Sauer Silencer Piston 9mm 1/2x28