Harvest-Master Pro Plus Grow Room Controller 

The Harvest-Master Pro Plus is the cadillac of climate controllers! Simply the most innovative controller on the market. And if you want the cadillac, but it doesn't fit your budget, order it w/o CO2 sensor, then add later! 

Harvest-Master Pro Plus Climate Controller provides automated climate control, CO2 dispensing and day length control, you can have you harvesting bigger, lusher and healthier crops, more often than ever before.

Just set the Growth Cycle you want: Vegetative, Fast Flowering or Full Flowering. This climate controller knows what it takes to achieve the optimum results.

Along with temperature and humidity sensors, there are 16 additional outputs (each needs relay switch) to control Lights, Exhaust fans, CO2, Cooling/Air Conditioner, Heating, Humidifier or Dehumidifier, etc.

Harvest-Master Pro Plus Climate Controller includes sensors for temperature, humidity and CO2, plus four (4) relay switches for lights, fans, CO2, air-conditioner or heater. Also has a spare ouput for timer.

More info from the Manufacturer (PDF format - Lots of detail.)