A tube coupling nut with the shank end accommodating a smaller tube size than is accommodated by the tube fitting which connects to the threaded end.
NSN 6130-01-621-4074
NSN 6320-00-853-1920
NSN 5895-01-349-7687
NSN 5925-00-052-5874
NSN 6135-01-122-2656
NSN 6145-01-445-7167
NSN 6220-01-085-2797
NSN 5915-00-280-1428
NSN 5990-01-150-7443
NSN 5920-01-595-7650
NSN 5965-01-335-6630
NSN 6105-01-239-7626