GrovTec GTHM244, Pistol Thread Protector, Black Oxide Finish, Black, 1/2X28 Threaded, .641 Diameter, Fits Aftermarket 9MM Barrels GTHM244 GrovTec's Thread Protector's are the perfect choice for protecting your threaded barrel. Available in popular thread pitches and exterior diameters" GrovTec's Thread Protectors will give your barrel a lifetime of protection and keep your threads in perfect working condition.