5310-01-386-9059 (37-320)
NSN 5310-01-386-9059 (NIIN 01-386-9059) is a lock washer in Federal Supply Class 5310, Nuts And Washers — a washer, usually round, with a centrally-located hole. Manufacturer part number 37-320 (Prestolite Electric Inc, CAGE 24975); also referenced as 66X-0201 (Prestolite Electric Inc).
Key specs: 38 to 46 rockwell c hardness; full characteristics table below. NIIN assigned February 1994; DEMIL A (none required); unit of issue HD (hundred), $9.32 gov standard price.