Knife Thread Insert, 1/4"-20 Int Thrd Sz, 1/2 in L, Steel, Plain, 20 PK, Midwest Fastener, Mfr#: 68642

An insert nut provides a threaded socket for a wooden workpiece, similar to a wall anchor. Insert nuts are inserted into a pre-drilled hole by one of two means: screw in and hammer in. In both cases, the external protrusions bite into the wood, preventing the nut from either turning or pulling out. They can be installed from one side of the workpiece.