Get precise control of your aquarium temperature with the Precision Submersible Heater. This Heater combines an adjustable temperature dial a high visibility temperature display and an advanced heating element to keep your aquarium water at the optimal temperature for your freshwater or saltwater fish. The Precision heater also includes a thermal switch which will turn off once it rises above an internal pre-set temperature and turns back on once it cools down making your aquarium safer for you and your fish.