Compact and sleek SMG Kit for the AAP-01 Comes with 3d prints only, you need the following hardware: 8 M3x8mm screw is used to fix the RMR/front sight/rail piece. 8 M3x12mm screw is used to fix the back unit. 1 M5x8mm screw is used to fix the stock. 2 M5x30mm screw is used to mag holder.