Honeywell S437A1025 SPST Sail Switch 1-1/2" X 4"

The Honeywell S437A1025 Sail Switch is a mechanical airflow-operated switch used in HVAC systems to sense and react to the air flow. The component has a 1-1/2" by 4" sail, which is moved by airflow and closes or opens its single-pole, single-throw contact to indicate system controls. It is normally fitted in air handlers, furnaces, and ventilation ducts where verification of airflow of the blower or draft is needed to ensure that they are functioning correctly. This sail switch is an airflow feedback element of the overall system.