Anderson Metals – 54048-1006 Brass 5/8″ Flare x 3/8″ NPT Male, Copper
This fitting can be used with copper, brass, aluminum, or steel tubing to connect and disconnect two tubes more easily than with a coupling. It has a flared tube connection on one end and a male National Pipe Taper (NPT) connection on the other for connecting to a female NPT threaded tube, creating a tighter seal than straight threads.