Our new AR stock adapter makes it easy to add a two bolt style (ACE) stock, Choate stock or our modular, custom billet rear stock to your Century Arms C39 AK pistol using our adapter attaching to the rear of your receiver through the sling hole. Please call with any questions. This part number for the Adapter only, other parts sold separately.(patent pending) NFA rules apply.***THIS REAR STOCK ADAPTER DOES NOT FIT THE V2 VERSION, V2 Flat mount listed down the page.