D-D DUAL TEMP CONTROLLERThe D D Dual Temperature Controller is an ideal way to keep the temperature of your aquarium stable. Temperature is continuously monitored by way of a temperature probe connected to the unit and temperature is regulated by one of two sockets on the device. Socket 1: Controls a heater within a certain desired temperature range, if the temperature drops below the required range the heater will be activated to warm your aquarium. Socket 2: Controls a