5310-00-199-5245 (600)
NSN 5310-00-199-5245 (NIIN 00-199-5245) is a hexagon slotted plain nut in Federal Supply Class 5310, Nuts And Washers — a nut having a flat bearing surface and 6 flat sides with slots in its upper portion. Manufacturer part number 600 (Naval Ordnance Standards, CAGE 94135).
NIIN assigned January 1961; DEMIL A (none required).