3/8" NPTM, 1/4" NPTM Brass Hex Nipple Threads conform with the American standard taper pipe thread & resist vibration. Tighten a minimum of 2-1/2 turns after hand tightening for air tight seal. Recommended uses include copper, brass, & iron. Working temp (pressure): -65 degrees F to 250 degrees F (1000 psi). Applications include oil, water, air, & natural gas. AGS brass and steel fittings are comprised of Tube Nuts, Unions (Couplers), Adapters, Elbows, Tees, Bushings, Connectors, Grease, etc... AGS fittings are held to the strictest standards to perform flawlessly in their intended applications. Fittings are offered in a variety of packaging options, including: retail clam-shells, bulk boxed, and plastic tray assortments.