Din 982 Nylook Nut

A Nylock nut is a type of lock nut with a nylon collar insert that resists turning. The nylon insert is located at the top of the nut and slightly smaller than the major diameter of the screw. When the nut is tightened, the nylon insert deforms elastically to grip the threads of the bolt, providing resistance to loosening caused by vibration and torque.