The International Comfort Products 1191249 SPST Pressure Switch (-0.27 Inch) is a reliable safety control designed for HVAC systems. This switch monitors and regulates air pressure within the furnace or air handler, ensuring proper system operation and preventing unsafe conditions. When pressure levels fall outside the specified range, it opens or closes the circuit to protect equipment. https://www.partshnc.com/42wc-spst-pressure-switch-3