This brake features a 22x.75 thread for saiga 12 shotguns. It also fits other shotguns such as the Vepre 12, DDI 12, and all shotguns with a 22x.75 thread for muzzle devices. Most shotgun barrels have an outside diameter of around 22 millimeters. They can be easily threaded with a 22x.75 die. The brake is made of 1018 steel. Besides being a breacher break it also reduces recoil immensely. ( Disclaimer-ends are very sharp) This brake comes with a jam nut to make timing this brake a breeze.