NPT THREAD SIZE & FITMENT: Fits standard 1/2" NPT Female to 1/2" NPT Female coupling adapter threads. NPT is a nominal pipe size, not actual diameter. Approx. 0.75" ID × 0.75" ID. Please confirm size before ordering. Not compatible with compression fittings. Premium Materials: Brass for corrosion resistance, ductility at high temperatures, and low magnetic permeability Wide Application: This pipe fitting can apply to water, air, gas, oil, and fuel High Quality Threads: High quality and deep threads allow the fittings to bite better, not easy to slip Note: This product can expose you to chemicals including lead(1.8%~3.7%), which is not allowed by federal law to be installed for potable water use in the U.S.A. and its territories Female National Pipe Taper (NPT) threads for connecting to male threaded pipes. Note: This product can expose you to chemicals including lead(1.8%~3.7%), which is not allowed by federal law to be installed for potable water use in the U.S.A. and its territories.