CO2 Monitor Controller Model # 2002A and 2002B by Control Wizard. This combo has been designed to turn CO2 equipment ON and OFF at pre-set levels by reading the Monitors signal output. When the exhaust fans are powered, the Controller will automatically turn your CO2 equipment OFF. This saves CO2 from being vented while the area is being cooled. When the exhaust fans shut OFF, the CO2 equipment is allowed to fill the room to your pre-set levels. The Monitor reads from 0-5000 PPM CO2. Pre-set levels are adjusted within the monitor (1500 PPM is optimum). The comfort or working zone is + or - 150 PPM.