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 5945-01-088-8071
NSN 6130-00-361-7114
NSN 5930-01-528-2541
NSN 6610-00-446-1775
NSN 6135-01-443-7716
NSN 5950-01-568-4943
NSN 6145-01-618-2500
NSN 6610-01-460-4864
NSN 5910-01-647-1555
NSN 5960-01-588-5681
NSN 5960-01-641-5493
NSN 5965-01-178-2367