Aquatic Life Pulse Saltwater & Freshwater LED Aquarium Light Fixtures Adjustable aquarium frame mounts accommodate aquariums between 46.75 and 55.75 Inch long and lock in place for a secure installation Glass LED lens covers help protect LED's and internal components Timer Daylight Mode allows the fixture to have programmed start and stop times while using a pre-programmed light intensity for each channel Timer Auto Mode allows for custom programming of the color and white LED's intensity, start and stop times and moonlight functionality Built-in battery backup prevents resetting timer after a power outage