The Zoo Med Reptitemp Digital Thermostat allows you to maintain precise control of your terrarium temperature with an easy-to-program LCD interface. Just plug in your heating device (up to 600 watts) or cooling device (up to 150 watts), set the desired temperature and mode, and let the Reptitemp handle the rest! The Reptitemp Thermostat controls temperature by turning on heating devices in "Heat" mode or by turning on cooling devices (such as a fan) in "Cool" mode. When the tank temperature strays above or below the set temperature, the Reptitemp will activate the device to raise or lower temperature until it returns to the proper level. An alarm feature may be enabled to alert you when the temperature is above or below the programmed settings.