The Zoo Med AquaSun Dual Timer enables you to simulate a natural day/night cycle for your fish, plants, and corals. Once set to the schedule of your choosing, this 24 hour analog timer turns your lights on and off automatically. It features a top outlet that is controlled by the integrated timer, and a bottom outlet that is always powered (perfect for air pumps, heaters, powerheads, etc.). The AquaSun Dual Timer comes equipped with a manual override which bypasses the timer schedule to offer continuous power in both outlets. It is compatible with all types of aquarium lighting, and uses grounded 3 prong receptacles for safety.