This is the perfect set up if you want the feel and length of a 6 position adjustable AR stock and the strength of our new fixed stock bracket. It bolts to your gun using the existing threaded hole on the rear underside of your gun . It will not wiggle out during fire and has a tight precision fit. The addition of the AR stock will greatly improve accuracy and shot grouping as it provides a firm shoulder rest and helps to balance the weapon. Upgrade your MAC today and save some money! Installation instructions & allen wrench included. This part number for semi auto only, see other categories for SMG components. NFA rules apply, Addition of this item may require additional paperwork to be filed with the ATF, check with your local dealers. (gun and other accessories sold separately) Length of adapter to the end of the extended stock is 11.5". Adapters are coated in flat black, shown in last photos.**TELL US IN THE COMMENTS SECTION OF YOUR ORDER IF YOU HAVE AN OPEN BOLT MAC-10, WE NEED TO GIVE YOU A DIFFERENT BOLT AND INNER THREADED BLOCK.