This is a MICROclimate B1 Reptile Digital Dimming Thermostat for Terrariums Snakes, Lizard. The Dimmer B1 Thermostat allows precise control of any heat source up to 600w by using advanced microprocessor technology. The B1 is a dimming thermostat that gradually varies the power supplied to the heat source for a smooth change in temperature inside the vivarium. A recessed temperature control adjuster is used to prevent accidental temperature changes if the unit were to be knocked which would be easily done if the dial protruded from the casing. A yellow LED provides real time feedback as to how much power is being supplied to the heater. Long cable lengths ensure the unit can be fitted easily into most vivarium setups.