Brand New, Factory-Sealed Kidde 2-in-1 Wireless Combination Smoke and Carbon Monoxide Alarm provides two important safety devices in a single unit. 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. Alarm can be installed as a single unit, or in a multiple station configuration that will enable wireless communication with the other alarms in the case of a smoke or CO event.