Asme b 18.2.2
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.)
NSN 6150-01-326-7064
NSN 6150-00-151-6771
NSN 5920-01-431-2174
NSN 6645-01-525-7493
NSN 5998-00-092-5937
NSN 5998-00-585-3171
NSN 6650-01-196-4667
NSN 2925-01-484-8556
NSN 6135-01-424-8130
NSN 4140-01-318-3087
NSN 6130-00-823-5359
NSN 6220-01-239-0559