The Titan Controls 702600 Apollo 1 is an innovative repeat cycle timer with photocell developed specifically for precise timing requirements. Repeat cycle means that when it is connected to a power source, the timer will recycle or "repeat" its ON and OFF timing schedule until power is removed. Designed to successfully run CO2 systems, hydroponic pumps, and exhaust fans, it provides full control of your grow gear, giving your plants the ideal growing environment. The built-in photocell allows the grower to use in daytime only, nighttime only or both day and night conditions. A 6-foot 'piggyback' style cord set makes this controller simple to hook up to your equipment.