1These four-pronged T nuts are made from carbon steel and plated with zinc for rust and corrosion protection 2These nuts are used to provide a strong, reliable and easy to fit threaded socket in wood and chipboard 3Convenient to use, simply tap these nuts into a suitably sized hole and the prongs will hold them in position 4These four prongs will stop the T nut from turning when they are inserted and tightened into wood pieces 5There are 5 different sizes nuts in this set that comes in a resealable assorted box for easy carry and storage