This Full Nut Nylock kit contains 92 pieces. These nylocks are grade 8 with a self locking nylon insert in the thread. Full height national fine threads for high torque use. They are designed to increase locking force and prevent the nut from coming loose. Zinc plated. Also known a nyloc nuts, there are several different sizes available in this kit. (25) 1/4", (20) 5/16", (20) 3/8", (15) 7/16", (12) 1/2".