1/8 in thread size thermostat fan switch for automotive applications. Temperature controlled cooling: the fan activates at 200 F and deactivates at 185 F, providing reliable engine cooling and temperature regulation. Reliable circuit activation: closes the circuit at the turnon temperature to activate the radiator cooling fan for engine cooling. Tailored cooling cycle: the turnoff temperature is always 15 F lower than the turnon, ensuring proper cooling cycles to prevent overheating. Broad compatibility: designed for installation and compatibility with a variety of automotive applications using a standard 1/8 in thread size. Clear, straightforward operation: simple, automatic control of the radiator fan based on coolant temperature without needing additional electronics or complex wiring. Two to three practical use scenarios Classic or older vehicles: a worn or failed fan switch to restore automatic fan control and prevent overheating during hot days or city driving. Vehicles with aftermarket radiators or electric fans: ideal for systems that require an explicit temperature switch to govern fan operation for reliable cooling. temperature environments or demanding use: suitable for towing, hot climates, or performance driving where consistent cooling cycles help protect the engine. This thermostat fan switch offers a simple, dependable solution for automatic radiator fan control, helping maintain engine temperature across a range of automotive applications.