The CO transmitter monitors carbon monoxide (CO) levels and is designed for the continuous monitoring of vehicle exhaust in non-hazardous areas.  The CO uses a wide spectrum, long life electrochemical sensor to measure the amount of carbon monoxide in the environment. It is offered with an operating range of 0 to 125 ppm. Both the Room and Duct CO transmitters are offered in a standard NEMA 1 rated ABS Polycarbonate plastic enclosure. An optional NEMA 4X watertight and dust proof enclosure is only available with the CO room transmitter. Other options include an LCD display with (2) SPDT Form 1C relays and a buzzer.  the CO Series is covered by ACI's Two (2) Year Limited Warranty.