The Sentinel Combination Carbon Monoxide and Smoke Alarm provides 2 important safety devices in a single unit. This alarm includes a voice warning system that announces Fire, Carbon Monoxide, Low Battery and Smart Hush Activation. The voice alarm eliminates any confusion and clearly warns you and your family of a smoke or carbon monoxide danger or if your battery is in need of replacement. This technologically advanced combination alarm is battery operated protecting you and your family even during a power outage when many incidences occur.