Yankee Hill Machine Rifle Thread Protectors screw onto your current threads to protect them from the abuse a gun goes through during the year. The tip of every gun gets swung around and can be bumped and dented. Muzzle devices are usually not intended as permanent additions to your weapon. The way to protect these additions is to take them off occasionally, or for the majority of the time and put on one of these protectors to keep the thread unaltered. Constructed of stainless steel and black plated, these thread protectors are very durable.