The Complete Greenhouse Controller handles every aspect of an indoor garden, from the lighting to the exhaust to the supplemental CO2. The Complete Greenhouse Controller features a 24 hour time clock, 2 outlets for lights, 2 outlets for exhaust fans, thermostat and humistat for temperature and humidity control, 2 pump outlets controlled by a cycle timer and 2 outlets for supplemental CO2 controlled by a cycle timer. It is upgradable for PPM Co2 control at any time. It ensures that CO2 production turns off while the exhaust is on and at night. 3 year no hassle warranty.