Hex nipple 3/8" x 1/8" Npt Solid Brass Reducing Hex Nipple American Pipe Thread
Recommended for grease, refrigeration, instrumentation and hydraulic systems. Use with brass, bronze, and iron pipe.
Brass, 3/8" Male NPT x 1/8" Male NPT
See photos with ruler 1/8 and 3/8 pipe thread measure much larger.