Colonel Mustard thread protector. A useful item to protect your threaded barrel for when you don't want to use a muzzle brake or flash hider. Screws onto standard AR-15/M4/M16 ½" x 28 threaded barrels. This thread is also commonly used on .22 LR, .22 Mag and .17 HMR rifles. CMMB57223MB.
Part Number: CMMB57223MB