The Marley Engineered Products 4520-2030-000 Thermal Fuse is a safety component designed to protect HVAC heating equipment from excessive temperatures. Rated to activate at 144°C, it responds to abnormal heat by opening the electrical circuit, stopping current flow and helping prevent overheating or potential component damage. Commonly used in electric heaters, air curtains, and other... https://www.partshnc.com/4520-2030-000-marley-engineered-products-thermal-fuse-144c