This unique side folding aluminum stock adapter must be mount to an AR buffer tube style threaded adapter or base and then an AR type buffer tube with a rear stock can be mounted (threaded). May fold to the left or the right. Fits Commercial and Mil Spec tubes, does NOT work with regular buffers and buffer springs. Made of high strength aluminum, finished in black oxide. Locks in the open position and closed. This part number for (2) adapters. Light duty only, for pistol buffer tube mount only, not for use with arm braces or stabilizer blades.