American Volt radiator hose in-line fitting and 1/8 inch NPT port. Fixed turn-on electric cooling fan thermostat sensor switch. Circuit closes at turn-on temperature and grounds your fan. Turn-off temperature is always 15 degrees less than turn-on. Mounts anywhere along the radiator or condenser hose line. Measures all fluid/liquid including water, coolant and oil. Universal for any car, truck, automotive or hot rod project.