Carbon Monoxide Sensor ITI's American Sensor Carbon Monoxide sensor provides early warning of dangerous carbon monoxide gas levels. A pre-alarm warning feature indicates low levels of CO, and a built-in ITI Learn Mode transmitter reports information to an ITI alarm panel. The detector plugs into an AC power outlet and will operate for four hours without AC power using its internal rechargeable battery. Features: Test/reset button. Internal siren signals when CO is present.