VERY100 Hunting Universal Single Rail Picatinny Weaver Barrel Mount with 3 Slots Clamp on This item has six sizes of ring diameters due to the screws length, the pictures are all the max dia of the rings, hope you can understand. Solid Aluminum Construction with Matte Black Finish Smart 2 Piece Design for Clamping; Rail Type: Picatinny/Weaver Barrel Range: Diameter 21mm-34mm; Material: Aluminum Designed to mount flashlight or laser on hand pistols,rifles and shotgun