Nordic Components Shotgun Barrel Clamp, Designed for 12 Gauge MXT Extensions, Compatible with Most 12 Gauge Shotguns, Features 10-32 Threaded Hole on Each Side for Mounting Accessories and Rails, Not Compatible with Remington 887 (Requires NCBCL-12-887), Compatible with Mossberg Shotguns and Benelli Nova/SuperNova BCL-12-MB The Nordic Components heavy-walled shotgun barrel clamp provides extra rigidity for your magazine extension on shotguns with heavy/overbored barrels or large barrel-to-magazine offset" such as the Mossberg 590/590A1" 835" 935" 930SPX" and the Benelli Nova/Supernova. Each clamp half has a centrally-located 10-32 threaded hole to accept accessories" such as a sling stud" barrel clamp tac rail or QD sling mount.