The CM-6 Low Voltage monitor detects Carbon Monoxide (CO) in commercial facilities such as parking garages, boiler rooms, etc. It can be used as a stand-alone detector and controller and as an analog transducer for use with Macurco control panels and other systems – ETL Listed, LADBS Approved. The TX-6-ND Low Voltage monitor provides automatic fan control to help maintain acceptable levels of Nitrogen Dioxide (NO2) in parking garages, warehouses, and other and controller and as an analog transducer for use with Macurco control panels and other systems – ETL Listed.