5310-01-025-1663 (MS75009-16)
NSN 5310-01-025-1663 (NIIN 01-025-1663) is a lock washer in Federal Supply Class 5310, Nuts And Washers — a washer, usually round, with a centrally-located hole. Manufacturer part number MS75009-16 (Military Standards, CAGE 96906); also referenced as MS75009 (Military Standards); VBE616D1 (Thales Nederland).
NIIN assigned July 1976; DEMIL A (none required).