The Ranco digital temperature controller is a full featured, programmable thermostat that controls temperatures from -30 oF to 220 oF. Features a submersible remote sensor probe with an 8 foot cable and a liquid crystal display that shows the exact temperature at the probe. Features the ability to set the differential (the temperature range at which the cooling or heating unit starts and stops) from 1 to 30 oF. By setting the differential to a higher range, you can save energy and wear and tear on your refrigerator compressor. In addition to its use with a refrigerator or freezer, the digital controller can also control any electric heating device. Just like the mechanical temperature controller, no wiring is required- just plug the controller into any 110 volt outlet, plug the device you want to control into the digital controller, and run the sensor cord inside the space you want to be controlled. Instructions included.