RS PRO, Bright Zinc Plated Steel Lock Nut, DIN 985, M16

RS Pro Nylon Insert Nuts Zinc Plated

The RS Pro zinc plated locking nuts have a nylon insert. The nuts have been designed to remain secure despite severe vibration. Having a nylon insert makes the nut better at sealing the bolt thread against leaking water, oil and other liquids.
When you insert the mating bolt into the nylon insert, the thread from the bolt compresses the nylon.

Standards

DIN 985