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 
National Aeronautics and Space Administration 
Austria 
Finland 
Poland 
Brazil 
Spain 
Columbia 
Singapore 
Saudi Arabia 
Australia 
Canada 
New Zealand 
France 
Germany 
Republic of Korea 
United Kingdom 
Netherlands 
Portugal 
Italy 
Denmark 
Greece 
Turkey Classification: Nuts of iron or steel
NSN 6135-00-228-8140
NSN 6240-01-056-8691
NSN 6685-01-251-7864
NSN 6320-01-125-3361
NSN 5999-01-291-5003
NSN 5950-01-131-4426
NSN 5835-01-183-7467
NSN 5998-01-322-4850
NSN 7035-01-448-0716
NSN 5935-00-767-0788
NSN 6150-00-847-6692
NSN 5990-01-389-1196