Stainless Steel Nylon Hex Lock Nut:
A six sided internally threaded nut with a nylon collar on the back side. When a bolt engages with the collar, the threads and nylon form a tight fit, restricting movement of the bolt. These nuts are 18.8 Stainless Steel designed to be used with 18.8 Stainless Hardware. They are a good choice if using in a situation where vibration exists.
Use Lubrication or Anti-seize to prevent galling.