Truglo Red Dt Mnt Shotgun Rib RmrFrom target archery and crossbow hunting to carry pistols and tactical competition, TruGlo has accessories to improve your gear. Features : Designed to mount a dot optic to shotgun ventilated rib Fits 0. 236 in. (6mm) to 0. 395 in. (10mm) ventilated ribs width Optic stays with the barrel and maintains zero when changing barrels for different seasons Mounting hardware and tools included Rigid two clamp mounting system Allows optic to sit low on the rib