Tiger Rock AR-15 Steel 1/2x28 Threaded Muzzle Brake Jam Nut Black. The Tiger Rock Jam Nut serves to hold your muzzle brake securely in place. Made from steel and designed for 1/2inx28 threaded muzzles this jam nut will keep your muzzle brake securely in place. Tiger Rock's Steel Threaded Muzzle Brake Jam Nut comes in a wide variety of standard metric and Imperial thread counts; so you can be confident in the quality of your purchase. Additionally our Steel Threaded Muzzle Brake Jam Nut functions as a jam nut for nearly any jam nut or blaster jam nut thread pitches. Package Contents: Tiger Rock AR-15 Steel 1/2inx28 Threaded Muzzle Brake Jam Nut Tiger Rock JN2: AR-15 Steel 1/2x28 Threaded Muzzle Brake Jam Nut Black