Primary Weapons Systems Mil-Spec, Ratchet Lock Castle Nut & End Plate Set, MOD 2, Fits Mil-Spec & Commercial size buffer tubes, Retail Packaging 4BTRLPB-1F The Ratchet Lock Castle Nut End Plate set works with mil-spec OR commercial buffer tubes and eliminates the need for staking. A quick upgrade to any rifle build" the Ratchet Lock Castle Nut End Plate features a QD mount and easy installation with any buffer tube.