The Marineland InLine LED Timer works with any of the Marineland Fully Adjustable Essential LED Lights and Marineland Fully Adjustable Advanced LED Lights. The Timer is connected in line to the power supply of the Marineland LED Lights. The Timer will turn the light on and turn the light off at a set point during the day. You can also have the light employ an automatic 15 minute long sunrise gradual ramp up period when the light turns on and a 15 minute long sunset dim down period when the light turns off. There are also manual buttons to increase and decrease brightness.