Sage International Shotgun Barrel/Magazine Clamp (Battleclamp) has a very nice smooth design with rounded edges. It stabilizes the magazine extension by clamping it to the barrel. That way, you will not damage the extension if you hit something with it. The Sage International clamp fits Remington 870, 1100, 11-87 and Benelli M1, M2, M4, M1014, 12 gauge shotguns.