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 6130-01-493-2291
NSN 5960-01-141-7584
NSN 5920-01-415-5805
NSN 5999-01-583-2886
NSN 5915-01-604-9868
NSN 6645-01-364-7330
NSN 6135-01-368-2785
NSN 5910-00-480-7340
NSN 6320-00-228-5678
NSN 5945-01-634-0588
NSN 5950-01-151-2581
NSN 6610-00-848-4764