A plain nut on which has been assembled a nonremovable washer.
NSN 6145-01-054-3874
NSN 5925-00-452-1270
NSN 6150-01-157-8726
NSN 2925-01-371-6853
NSN 5905-01-233-2040
NSN 5950-01-431-7311
NSN 6130-01-542-3780
NSN 5960-01-523-9098
NSN 5945-01-084-1557
NSN 5910-01-533-2403
NSN 7035-01-211-5636
NSN 6610-00-469-3459