Use this analog unit to control the temperature of a refrigerator, freezer, or air conditioner. It enables you to ferment and store beer at correct temperatures when the ambient room temperature is too warm. Your electrical cooling device plugs into this unit which plugs into the outlet. A remote sensor connected by a small capillary tube monitors temperatures. If the temperature rises above your set point, the cooling device is turned on. The unit features a 4 degree swing to help extend the life of the cooling unit's compressor. For example, if you had it set at 68 degrees, it would turn on at 68 degrees and go to 64 degrees before turning off. The unit has the potential to regulate temperature from 20 to 80 degrees Fahrenheit. The sensor tube can be inserted into a refrigerator or freezer, and still allows the door gasket to seal tight. Temperature Range of 20 to 80F. This Johnson unit can handle 15 amps or 1725 watts at 115 volts AC.