Called nut
No other part numbers with same form, fit, and function found.
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 5895-01-202-1288
NSN 6135-01-504-4309
NSN 5965-01-185-7354
NSN 6105-01-007-9915
NSN 6150-00-844-0254
NSN 5999-01-071-4221
NSN 7035-01-645-8589
NSN 5945-01-626-4693
NSN 7035-01-424-7019
NSN 6110-01-048-0427
NSN 2925-01-254-3068
NSN 6645-00-440-5635