Elliptical locking feature id
A soft metal or nonmetal sleeve, designed to mate with a pin-rivet. it may include an external wrenching facility which breaks off at a perdetermined torque to form a head.
NSN 6145-01-374-1899
NSN 6110-00-719-7209
NSN 5935-01-108-0092
NSN 5950-00-730-0218
NSN 6610-01-648-4460
NSN 5835-00-980-0468
NSN 5975-01-318-4742
NSN 4140-01-605-7280
NSN 4140-00-658-7271
NSN 5920-01-606-8573
NSN 6130-00-573-0622
NSN 5905-01-465-9600