The International Comfort Products 1191249 SPST Pressure Switch (-0.27" WC) is a reliable safety control designed to monitor and verify proper air pressure within HVAC systems. It operates by sensing negative pressure created by the inducer motor and closes or opens the electrical circuit when the required pressure level is reached, helping ensure safe equipment operation. Commonly us... https://www.partshnc.com/42wc-spst-pressure-switch-3