This SBM4 complete kit, is ready-to-assemble on your Mossberg 590 Shockwave, greatly enhancing the usability of the firearm by adding a third point of contact for stabilization. It includes: SBM4 pistol stabilizing brace; STDT-C pistol receiver extension; ERGO Flat Top SUREGRIP and Mossberg 590 adapter; castle nut; adjustable nylon strap.
This model is compatible with your 410 gauge 590 Shockwave.