The SF RYDER 9 Piston is the threaded component used to attached the SureFire RYDER 9 or RYDER 9M Suppressor to threaded barrel of the host weapon. The piston comes standard with the specified suppressor; however, the piston is also sold separately to change thread option as needed. Length: 1.875" (4.76cm) Weight: 1.1oz (31.2g) Construction: Stainless Steel Single-point M13.5×1 LH thread Simple Installation Designed and built in the USA Mfg: Surefire