This valve is used for temperature and pressure relief and is constructed of brass metal with a 4" epoxy-coated probe. The epoxy coating on the probe prevents the build-up of corrosion to help keep things functioning smoothly. The inlet connection is national pipe tapered while the outlet connection is MNPT, with the outlet connection size measuring 1/2". This valve protects the water heater from high water temperatures and pressure and is pre-set to 150 PSI and 210 degrees Fahrenheit. This valve is CSA certified and weighs about 8 ounces. The valve is rated for about 15,000 BTUs.