Convert your SRD9 or SRD45 suppressor to a 13.5x1mm Left Hand thread pitch with the SRD-PISTON-M135X1LH. The piston is made of 17-4 heat treated stainless steel with a matte glass bead finish. The piston will fit a variety of hosts and it is a perfect choice for converting your SRD45 to 9mm. Simply swap the conversion piston with the original piston in your suppressor to match your barrel thread pattern.