Stainless steel thread protector for 1/2x28 threaded 9mm pistol barrels. It shields the muzzle threads when no compensator or suppressor is installed, keeping the threads clean and undamaged in storage and carry. Features: 1/2x28 thread pitch (9mm) Stainless steel construction Knurled body for hand tightening Pre-installed O-ring for retention Fits Glock-pattern, Sig, and Smith & Wesson barrels, along with other pistol barrels cut to 1/2x28. Confirm your barrel thread pitch before ordering. GLOCK is a registered trademark of GLOCK Inc. 3CR Tactical is not affiliated with, endorsed by, or sponsored by GLOCK Inc. Any reference to GLOCK products is for identification and compatibility purposes only.