Kidde KN-COSM-IBA Hardwire Combination Smoke/Carbon Monoxide Alarm with Battery Backup and Voice Warning, Interconnectable (2 Pack)

The Kidde KN-COSM-IBA uses breakthrough technology to offer a fast response to real fires, including smoldering and fast-flaming, as well as protect you from carbon monoxide and dramatically reduce the chance of nuisance alarms.
The Intelligent sensor technology combines the detection capabilities of an ionization smoke sensor - which is more likely to detect smaller, less visible fire particles, like those produced by flaming fires - with that of an electrochemical sensor, which is used to detect CO.
Since carbon monoxide is present in all fires, having both detection chambers work together in one alarm is a breakthrough in the fire safety industry.
When either sensor notices a potential hazard, it will communicate with the other. Depending on what is detected, the alarm will adjust its smoke sensitivity in order to better discriminate between a real hazard and a false one.
This constant communication enhances the alarm's overall performance in all fires, and significantly reduces the potential for a nuisance alarm.