AN365-4 ELASTIC STOP NUT 1/4-28

Cad plated steel with fiber insert gives a friction grip on the threads of the bolt so it holds secure.  Also called self locking nut, fiber lock or Nylock.   125,000 psi tensile strength, heat to 250 degrees. The
AN365 series is the standard, full height lock nut. The AN365
specification is equivalent to the MS20365 and newer MS21044
specification.