5310-01-493-5501 (2154)
NSN 5310-01-493-5501 (NIIN 01-493-5501) is a lock washer in Federal Supply Class 5310, Nuts And Washers — a washer, usually round, with a centrally-located hole. Manufacturer part number 2154; also referenced as 2154 2233-165 (Macgregor USA Inc.).
NIIN assigned January 2002; DEMIL A (none required); ESD/EMI-sensitive; unit of issue EA (each), $0.93 gov standard price.