5310-01-224-1407 (420)
NSN 5310-01-224-1407 (NIIN 01-224-1407) is a lock washer in Federal Supply Class 5310, Nuts And Washers — a washer, usually round, with a centrally-located hole. Manufacturer part number 420; also referenced as 420 945 752 (Naval Inventory Control Point).
NIIN assigned January 1986; DEMIL A (none required); ESD/EMI-sensitive; unit of issue EA (each), $0.33 gov standard price.