This is the right component if you want the feel and comfort of an adjustable AR stock. It bolts to your gun and maintains a tight precision fit under rapid fire with the aid of a machined set screw and use of a standard AR locking ring. 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. *Addition of this item may require additional paperwork to be filed with the ATF, check with your local dealers. This part number is for the adapter only for all Master Piece Arms 9mm guns, 30, 30T, 35, 35SST, & 20SST. You will need an AR rear stock to complete the setup. See other parts numbers for complete set up. (gun and other accessories sold separately) Installation instructions & Allen wrench included. Works with most commercial and mil spec sized AR type rear stocks & pistol buffer tubes. Fits 5.7x28mm with Threaded slot on underside of rear receiver. Matte/Flat Black finish. **DOES NOT FIT NEWER 9MM MODELS-Fits all Master Piece Arms 9mm guns and rifles only with a factory threaded hole at the rear underside of receiver.