The Kidde KN-COSM-IBACA 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. Combined smoke and carbon monoxide alarm - a single unit can be installed where previously, two were needed, reduces installation time and protects against both fire and carbon monoxide dangers Intelligent sensor technology - combines the detection capabilities of an ionization smoke sensor with that of an electrochemical carbon monoxide sensor Voice warning - announces the hazard type detected (in english and french), alarm announces "fire!" when a smoke or fire hazard is detected and announces "warning! carbon monoxide!" when a co hazard is detected, also announces "low battery" when it is time to replace the batteries 120 V interconnectable - will interconnect with up to 24 other devices (18 of which can be initiating), including smoke alarms (limit of 12), co and heat alarms AA front-loading battery backup - change batteries without the need to remove the unit from the ceiling, providing continuous protection in the case of a power outage