5310-01-236-2139 (BACW10BP20P)
NSN 5310-01-236-2139 (NIIN 01-236-2139) 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 BACW10BP20P (The Boeing Company, CAGE 81205).
Key specs: 36 to 40 rockwell c hardness; full characteristics table below. NIIN assigned July 1986; DEMIL A (none required); unit of issue EA (each), $5.61 gov standard price.