5310-00-199-3109 (MILS1222)
NSN 5310-00-199-3109 (NIIN 00-199-3109) is a hexagon plain nut in Federal Supply Class 5310, Nuts And Washers — a nut, flat on top and bottom having 6 flat sides. Manufacturer part number MILS1222 (Military Specifications, CAGE 81349).
Key specs: 187 brinell standard nominal hardness; full characteristics table below. NIIN assigned January 1963; DEMIL A (none required). Related NSN 5310-00-753-8406.