The Dungs Pressure Switches 266945 Gas Pressure Switch is used to measure and regulate the pressure of the gas in HVAC systems. It has a 1/4” NPT connection and a pressure range of 1-20” WC to deliver consistent performance in different applications. It has a manual reset type that guarantees its correct operation after a pressure deviation. https://www.partshnc.com/266945-dungs-pressure-switches-1-20-inch-wc-mr-14-inch-npt-switch