1These four-pronged T nuts are made from zinc-plated carbon steel for rust and corrosion protection. 2These nuts are used to provide a strong, reliable and easy to fit threaded socket in wood and chipboard. 3These four prongs will stop the T nut from turning when they are inserted and tightened into wood pieces. 4There are 5 different sizes of T nuts that you can choose as need for different purposes and projects. 5Convenient to use, simply tap these nuts into a suitably sized hole and the prongs will hold them in position.