Anvil 2125 Forged Steel AAR Pipe Fitting, Class 3000, Union, 1/2" NPT Male x 1/2" NPT Female, Galvanized Finish Union for connecting and disconnecting two pipes more easily than couplings Male National Pipe Taper (NPT) threads on one end and female NPT threads on the other for connecting pipes with different ends Forged steel for weldability, rust resistance, and durability with a galvanized finish for a protective coating Association of American Railroads (AAR) class 3000 fitting for use in high-pressure applications Meets specifications ASTM A105 and ASME/ANSI B16.11 for quality assurance