Dual controller allows you to monitor the pH and ORP levels in your aquarium and to automate the dosing of CO2 and ozone. Electrode and 12-volt DC adapter included.The ORP control features include a selectable set point of 0 to 600mV, which will turn your ozonizer on when the reading falls below your set point. Accurate within 5mV.The pH control features include manual 2-point calibration, accuracy of .2 pH, set point range of 5.5 to 9.5 pH, and a visual alarm when reading is higher than the set-point.