The Dead Air Armament Ghost piston is made from tough and durable 17-4 PH stainless steel and had a black salt bath nitride finish that resists corrosion reduced friction and improves wear resistance for longer suppressor O-ring life. The oversized diameter provides more precise alignment. This piston has metric 16×1 LH threads. Dead Air Armament is all about bringing the best material manufacturing techniques and suppressor designers together. – Specifications and Features – Dead Air Armament DA406 – 17-4 PH stainless steel – Black nitride finish – Oversized diameter – M16x1 LH threads