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 5985-00-189-4186
NSN 6685-01-497-2729
NSN 4140-00-633-1435
NSN 5990-00-932-3070
NSN 5935-01-006-4217
NSN 4140-01-411-0460
NSN 6685-00-284-1070
NSN 5855-01-504-6080
NSN 5950-00-375-6092
NSN 2925-01-376-9236
NSN 5935-01-315-9264
NSN 5950-01-620-9003