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.