Std mil-spec part - Sniper AR-15/M16 Receiver Extension Mil Spec Castle Nuts

Standard Mil-Spec buffer tube castle nut, or receiver extension tube nut. Threaded smoothly, didn't mar easily, staked well, no issues. When installing, I suggest using some anti-seize, or a drop or two of oil on the threads to ease the threading process and prevent galling of those threads on the lower receiver, the receiver extension tube, and the castle nut itself.