This digital controller can be switched from cooling to heating with a jumper inside the case. A liquid crystal display indicates the exact temperature (accurate to plus or minus 1.5-) at the submersible probe, so there is no need to use an additional thermometer to monitor fermentation temperature. The liquid crystal display shows either a small snowflake or flame to indicate whether the control is in cooling or heating mode. The display is easily switchable from Fahrenheit to centigrade display. An indicator LED light turns on when the control is providing power. The Controller II features an adjustable differential (between 1- - 30-) to help save wear and tear on your refrigerator, freezer, or air conditioner compressor and is accurate to plus or minus 1.5- over its entire range of -20-F. to 200-FYou control the differential, balancing the capabilities of your cooling unit with your desire for a precise setting. The submersible .235" inch diameter stainless steel probe can be put in a small bottle of water to get a true reading of the liquid inside. Besides an adjustable differential, you can control if the Controller II provides power when the differential is reached, or cuts out. For example, if the unit is set for cooling at 55-F. (with a 3- differential) you want it to turn off when it cools down to the 52- differential setting. However, set it for heating at 55-F., and you will want it to turn on when the temperature drops to the 52- differential. The Controller II features jumper selectable cut in and cut out points, so you can perfectly tailor it to a cooling or heating application. The Controller II features a 6' power cord, a 6' outlet cord, and a 6' sensor cord with a .235" diameter stainless steel submersible sensor. The blue plastic body is 5" long, 2.5" wide, and 2.4" deep. Screw holes in the back of the case are provided for mounting.