The Zoo Med AquaSun Aquarium Timer enables you to simulate a natural day/night cycle for your fish, plants, and corals. It turns your lights on and off automatically, giving you one less thing to worry about. The 24 hour AquaSun Timer is compatible with all types of aquarium lighting and is super-easy to install and program. It comes equipped with an LED indicator light to show active operation and a manual override which bypasses the timer schedule to offer continuous power. For safety, the Zoo Med AquaSun Aquarium Timer features a 3 prong grounded receptacle.