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 
National Security Agency 
U.s. Marine Corps 
Dept. of the Navy 
Federal Aviation Administration
Federal Aviation Administration 
U.s. Coast Guard 
National Weather Service 
National Aeronautics and Space Administration
National Aeronautics and Space Administration
National Aeronautics and Space Administration 
Austria 
Finland 
Lithuania 
Poland 
Brazil 
Spain 
Columbia 
Israel 
Singapore 
Kuwait 
Morocco 
Saudi Arabia 
Malaysia 
Australia 
Belgium 
Canada 
South Africa 
New Zealand 
France 
Germany 
Republic of Korea 
United Kingdom 
Netherlands 
Portugal 
Italy 
Denmark 
Norway 
Greece 
Turkey 
NATO Maintenance and Supply Agency Classification: Nuts of iron or steel
NSN 5835-01-447-2544
NSN 7035-01-478-5922
NSN 6610-01-619-3928
NSN 6130-01-605-1850
NSN 5998-00-067-4316
NSN 6610-01-263-0425
NSN 5998-01-158-6809
NSN 6130-01-397-1917
NSN 6150-01-577-3964
NSN 6685-01-627-1237
NSN 5985-01-114-7247
NSN 5905-00-456-5930