The Cleveland Controls NS2-1199-00 Pressure Switch is an air pressure sensing device designed to monitor airflow or pressure conditions in HVAC equipment. It operates using a sensing diaphragm that responds to positive, negative, or differential air pressure and activates an integral snap-action electrical switch when the specified pressure condition is reached. It is used in furnaces... https://www.partshnc.com/ns2-1199-00-cleveland-controls-pressure-switch