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.

Greater resistance to vibrations and torque
Mild steel grade 8.8
Retains locking ability up to 250°C
Resistant to organic acids, solvent, oil and mineral salt
360° seal
Available from M5 to M20

Used by builders, DIY enthusiasts, joiners and Roofers.

If Zinc plated is not what you are looking for, we have the nylon insert nuts in A2 and A4 stainless steel.

DIN 985