A nylon insert grips the bolt to resist loosening without damaging threads. These locknuts are reusable, but their holding power lessens with each use. They are suitable for fastening most machinery and equipment. A zinc plating provides corrosion resistance in wet environments.

Also known as, Nylon insert Flange Lock nut, it is a kind of hex flange nut , with a nylon-filled collar at its back end and an enlarged circular base flaring out from the front end of the nut. When an extremely threaded fastener reaches the collar, the threads and nylon form a tight frictional fit, as the nylon applies downward pressure that forces contact between the internal and external threads. The nut may be reused up to 50 times, and it does not damage the threads of the fastener it is used with, withstands extreme vibrations without loosening.