A Mild Steel Hexagon Weld Nut consists of a flanged neoprene bushing with a nut embedded in the non-flanged end. The bolt is passed through one of the pieces to be fastened and threaded onto the nut from the flanged end. The non-flanged end is then inserted through the other piece to be fastened. As the bolt is tightened, friction from the neoprene flange against the piece being fastened prevents the nut from turning.
