M4 thread size automotive thermostat temperature switch. Closes circuit at temperature and passes power or ground. Select the temperature range that suits your project needs. Dual 1/4" inch standard pin electrical terminal connections. Sensor can measure both contact and liquid temperatures. American Volt M4 thread size automotive thermostat temperature switch. Closes circuit at temperature and passes power or ground. Select the temperature range that suits your project needs. Dual 1/4" inch standard pin electrical terminal connections. Sensor can measure both contact and liquid temperatures.