Machined 6061T6 Aluminum spacer and steel thread adapter allows the use of the Magpul Mossberg 590 SGA stock on the Stoeger M3k/M3000/M3500/P3000 series 12ga shotguns. Chrome-moly internal threaded insert converts factory 10mmx1 stock bolt thread to the Magpul’s 5/16-18 SAE thread. Matte Black anodized outer spacer creates a smooth transition between the Stoeger receiver and the Magpul stock. Still allows use of the factory stock shims for cast and drop adjustment! Drop-in parts, no fitting required. STOCK NOT INCLUDED. NOTE- ONLY WORKS WITH MAGPUL MAG490-series SGA stocks intended for the Mossberg 500/590/590A1 shotguns! Does NOT fit the Remington model. It may work with other stocks intended for the Mossberg 500/590, but some minor fitting may be required.