Nut has 3 round indentations equally spaced around the flats
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.)
Classification: Nuts of iron or steel
NSN 5915-00-393-1850
NSN 6135-00-235-1938
NSN 5998-00-070-5795
NSN 5996-01-444-5409
NSN 6610-00-585-9160
NSN 6620-01-159-4330
NSN 6320-01-275-3972
NSN 5930-00-889-4296
NSN 6150-01-437-9785
NSN 6110-01-176-6881
NSN 6105-01-401-5361
NSN 6110-01-547-2771