The Mako Group wrote: The Mako Group/FAB Defense Buttstock Kits for Remington 870 and Mossberg 500 AGRF870-FKSB/AGM500-FKSB Modular collapsible buttstock and pistol grip system for Mossberg 500/590 shotguns. Features a patented recoil-compensating system for unparalleled recoil reduction! Rugged one piece adapter design features drop-in installation. Correct angle for best recoil control. Textured for secure grip.