AquaTop DDC-800 Electronic Heater Controller NOT A HEATER; HEATER SOLD SEPERATLY Can be used with any heater for insuring precise measurement. It offers precise control to ensure stable water temperatures for all aquatic livestock (66F - 93F range). With a highly visible dual digital LED display, the DDC-800 includes adjustable high and low temperature settings with audio alerts. Utilizes heavy-duty, three-prong receptacles and offers overheating protection Each unit is equipped with a dual relay interwork that doubles the protection and safety of aquatic life by disabling the heating element in case of overheating