Detection Capabilities: It uses a Split-Spectrum Sensor to detect both fast-burning and smoldering fires, as well as a carbon monoxide sensor. Smart Features: The device speaks with a friendly voice to provide early warnings and can send alerts directly to your phone via the Nest app if you are away from home. Connectivity: It connects to your home's WiFi network and can interconnect wirelessly with other Nest Protect units. Ease of Installation: The battery-powered version is easy to install as it does not require hardwiring. Power Source: It operates on six AA Lithium batteries, designed for multi-year operation. New in box