The Kidde FireX ACDC 120-Volt Carbon monoxide alarm detects carbon monoxide. This hardwired 120-Volt Inter Connectable Carbon Monoxide Alarm with 9-Volt Backup can be interconnected with up to 24 Kidde devices, 18 of which can be initiation style (additional devices not included). The alarm has a fuel-cell design with a low-battery warning that issues a brief alarm chirp and a red LED light that will flash approximately every 15-seconds. Can be inter connected with up to 24 Kidde devices, 18 of which can be initiation style (additional devices not included). Compatible with smoke alarms, carbon monoxide alarms and heat alarms on 1 wiring network (alarms and wiring sold separately). Smart inter connect system enables the unit to alarm in a carbon monoxide pattern and sound a different pattern when inter connected to a Kidde smoke alarm that is in alarm mode (smoke alarm sold separately). Fuel-cell design with a low-battery warning that issues a brief alarm chirp and red LED light that will flash approximately every 15-seconds. Piezoelectric horn is rated at 85dB at 10 ft. Alarm will not sound if carbon monoxide levels are below 30 PPM. 9-Volt battery backup provides protection during power outages. Compatible with Kidde, FireX, Code One and Sentinel products. Meets sensitivity requirements of UL 2034 single and multiple-station carbon monoxide alarms. Carbon monoxide detector utilizes an electrochemical sensor to detect fire hazards and sounds an 85 db alarm when a hazard is detected. *Check with your state and local fire and Building/Safety codes for specific information regarding smoke & Carbon Monoxide Alarms. UL/CSFM Ref. Kidde Part KN-COB-IC.