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 6620-01-116-0486
NSN 5950-01-652-8426
NSN 6685-01-367-2927
NSN 5835-00-113-6090
NSN 5855-01-213-9076
NSN 6130-00-558-6112
NSN 6645-01-344-8702
NSN 5960-00-722-4140
NSN 5990-01-207-8684
NSN 6685-01-393-9027
NSN 6130-01-421-8304
NSN 6320-00-977-3930