Detects smoke and carbon monoxide. Voice alarms with custom location. Nest Protect sends phone alerts for smoke and carbon monoxide detection, low battery (battery model only), and sensor failure. Detects fast and slow burning fires. Silence from your phone using the Nest App. This alarm conforms to the latest British Standards, but further intervention may be required to wake sleeping children. Includes voice alerts which have been shown to be more likely to wake children than standard alarm.