5310-01-053-3983 (2018-29)
NSN 5310-01-053-3983 (NIIN 01-053-3983) is a key washer in Federal Supply Class 5310, Nuts And Washers — a washer of nonresilient material usually having two parallel bearing surfaces. Manufacturer part number 2018-29 (Janco Corporation, CAGE 91812); also referenced as 4M102-6 (The Boeing Company).
Key specs: 57 to 77 rockwell b hardness; full characteristics table below. NIIN assigned January 1978; DEMIL A (none required); unit of issue EA (each), $58.94 gov standard price.