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 6620-00-999-2425
NSN 5925-01-150-8127
NSN 5965-00-356-3838
NSN 5990-01-116-2181
NSN 6645-01-347-0450
NSN 5996-01-443-8755
NSN 6110-01-282-5807
NSN 6110-01-443-3785
NSN 6620-01-465-7615
NSN 6105-01-091-9985
NSN 6240-00-826-8426
NSN 5895-00-903-3458