5310-00-285-9637 (SP19921)
NSN 5310-00-285-9637 (NIIN 00-285-9637) is a flat washer in Federal Supply Class 5310, Nuts And Washers — a washer having a centrally located hole with a solid or laminated cross-section and two flat parallel bearing surfaces. Manufacturer part number SP19921 (Navair And Navsea Managed Original, CAGE 10001).
Key specs: 75 to 85 brinell standard hardness; full characteristics table below. NIIN assigned January 1963; DEMIL A (none required); unit of issue EA (each), $0.15 gov standard price; export Schedule B 4016.93.0000.