Tiger Rock Threaded Barrel Protector AR 9mm 1/2x36 Thread Pitch Silver Small. This threaded barrel protector offers excellent corrosion resistance with its Blackened Matte finish and 1/2inX36 threads. The AR 9MM 1/2inx36 Threaded Barrel Protector also acts as a thread protector in extreme circumstances where the barrel itself is damaged. If the barrel is damaged the protector alone can offer great protection. Do not fire the firearm with the protector on as it can compromise the reliability of the pistol. If the barrel is scoured or damaged in any way the impact of the blowback can cause permanent damage. The threads on the AR 9MM 1/2inx36 Threaded Barrel Protector can also cause permanent damage to the barrel. Do not use the thread protector on any .9mm threaded barrels. Specifications for Tiger Rock AR 9mm 1/2inx36 Threaded Barrel Protector: Manufacturer: Tiger Rock Caliber: 9mm Luger Package Contents: Tiger Rock AR 9MM 1/2inx36 Threaded Barrel Protector Tiger Rock M9MM-S: Threaded Barrel Protector AR 9mm 1/2x36 Thread Pitch Silver Small