Formed sheet metal nuts are also known as speed nuts or clip-on nuts. Speed nuts are designed with two sheet meal prongs that act as one thread which provides a full 360° grip. The more the screw is tightened enough force thru the prongs to the screw that it keeps it from loosening under vibration. They are a form of locknut which serves the functions of both lock washer and nut, which saves assembly time and money.