Description Use the Ergo Grip Stock Adaptor to install AR-15 type stocks and pistol grips on your Mossberg 500/590 shotguns. Accommodates mil spec or commercial buffer tubes. Use any style AR type collapsible buttstock and pistol grip combination Accommodates mil spec or commercial buffer tubes This stock adapter has the proper drop designed in, so factory sights can be used. (Bead, Rifle, and Ghost Ring Sights) Made from glass filled polymer Includes mounting hardware