A nut, flat on top and bottom having 6 flat sides. For items which have internal tapered or straight (parallel) pipe threads, specific electrical conduit size designation, and which when installed, provide a method of tightening to lock the connection, see locknut, electrical conduit. See also locknut, tube fitting. For items having a thickness (or height) exceeding two times the width across the flats, use post, electrical-mechanical equipment. (when height or thickness and/or width across the flats is designated as a tolerance dimension, the maximum dimension will be used to determine compliance.)
Dept. of the Army 
Dept. of the Air Force 
U.s. Marine Corps 
Dept. of the Navy 
Bureau of Prisons 
U.s. Coast Guard 
Bureau of Mines 
Bureau of Reclamation 
Bureau of Engraving and Printing 
Bureau of the Mint 
National Aeronautics and Space Administration
National Aeronautics and Space Administration
National Aeronautics and Space Administration
National Aeronautics and Space Administration 
General Services Administration 
Austria 
Hungary 
Lithuania 
Poland 
Bulgaria 
Brazil 
Spain 
Singapore 
Kuwait 
Morocco 
Malaysia 
Thailand 
Australia 
Belgium 
Canada 
New Zealand 
France 
Germany 
Republic of Korea 
United Kingdom 
Philippines 
Netherlands 
Portugal 
Italy 
Denmark 
Norway 
Greece 
Turkey 
NATO Maintenance and Supply Agency Classification: Nuts of iron or steel
NSN 6135-01-174-8057
NSN 5910-00-409-8543
NSN 5910-01-154-1890
NSN 6105-01-456-4488
NSN 6220-00-004-1744
NSN 6130-00-173-6062
NSN 5910-00-951-9692
NSN 5915-00-975-9917
NSN 5915-01-433-9666
NSN 5920-00-759-1003
NSN 2925-00-918-0859
NSN 6320-01-543-1194