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 6135-00-416-2898
NSN 5990-00-443-2743
NSN 5945-01-017-7199
NSN 6135-00-437-5182
NSN 7035-00-205-8739
NSN 5910-01-269-3253
NSN 7035-00-371-7749
NSN 5930-00-467-6808
NSN 2925-01-125-9169
NSN 5930-01-259-7858
NSN 5835-00-912-5656
NSN 5960-01-641-5493