With this easy-to-use timer, you can now automate the schedule of grow lights and exhaust fans in your hydroponics system, and never have to worry about forgetting to turn ON/OFF your lights/fans. In addition to hydroponics systems, this timer can also be used with household appliances. Operating Instructions: Unplug unit. Set duration of appliance to stay ON by pushing down the small segments. Each segment is 15 minutes. Set CURRENT time by turning the timer dial clockwise until the arrow points to the correct time. Plug appliance into timer. Plug timer into power outlet. Timer can be overridden by using the red sliding switch on the side. Package Content: (1x) timer