A nut is a fastener with a threaded hole. It has hexagonal, flanged and thrust plate types. These are named normal nut, lock nut, fibered nut in  the world. Nut is produced 8 quality,10 quality and 12 quality hardness value. From the thread of nut can be produced left or right thread as metric and inch norms. It is coating ZnCr+3, phosphate and geomet.