This is a 3/8 x 1/4 fnpt pipe to tube adapter
No other part numbers with same form, fit, and function found.
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 5999-01-141-9350
NSN 5950-01-502-9565
NSN 6130-01-056-7167
NSN 6130-01-415-3345
NSN 5895-01-629-2161
NSN 4140-01-456-5685
NSN 5965-01-225-1728
NSN 5999-01-122-1816
NSN 5999-01-334-7960
NSN 6620-01-367-4960
NSN 5998-00-739-8930
NSN 6110-01-172-5492