Apollo Valve 10-400 Series Bronze Safety Relief Valve, ASME Hot Water, 50 psi Set Pressure, 3/4" NPT Male x Female Relief pressure preset of 50 psi for releasing excess pressure 3/4" male NPT threaded inlet for connecting to a female NPT threaded connection ASTM B584 bronze body and nozzle and stainless steel spring for corrosion resistance 250 degrees F maximum temperature for use in high-temperature applications ASME safety rated for Section IV water heating systems