Wrenching facility - across flats is 0.6875 inches.
An adapter having standard pipe threads on one end or an unthreaded end designed to accommodate a pipe. The other end has machine threads (straight threads other than pipe or hose series) designed to accommodate a tube or is unthreaded and designed to accommodate a tube. It is designed to join a pipe or pipe fitting to a tube or tube fitting in a straight line.
NSN 5999-01-524-8766
NSN 5975-00-492-1587
NSN 7035-01-552-5836
NSN 6220-00-366-1670
NSN 2925-01-209-9245
NSN 5920-01-420-5768
NSN 6240-00-412-2307
NSN 6220-00-003-1644
NSN 5925-01-371-6994
NSN 6645-01-310-7348
NSN 5935-01-559-3580
NSN 5996-00-248-7061