This rugged, one-piece metal mount clamps onto the extended magazine tube for secure mounting of 1? diameter lights such as the Surefire 6P, 9P, or any other light with a 1? diameter body. It fits 12 gauge shotguns with extended or large capacity 1? diameter magazine tubes such as those by Choate, Scattergun Tech, TacStar, and the factory magazine tube. Fits: Remington 870/1100/1187; Mossberg 500/590/500A; Winchester 1200/1300