Plastic acetal
A nonmetallic unthreaded item generally round in cross-sectional shape which, when placed on/in a machined-out portion of the threads of a screw or bolt, or inserted into the machined-out portion of the threads of a nut, locks the item, to which it is fixed, to the attached mating member and prevents loosening during excessive vibration. Excludes bolt, self-locking; nut, self-locking (as modified); screw, self-locking; and insert, screw thread.
NSN 4140-01-322-7080
NSN 6110-01-633-9660
NSN 5905-00-446-2772
NSN 6145-01-657-3777
NSN 6150-01-051-3497
NSN 6620-01-254-3609
NSN 5996-00-413-4416
NSN 6650-00-629-8027
NSN 5935-01-415-0887
NSN 5905-01-188-2299
NSN 5935-01-078-4555
NSN 6135-01-244-5580