With the Google Nest Protect V2 - Battery, you are always aware of potential smoke development or carbon monoxide leaks in your home. Once the smoke and carbon monoxide detector is mounted on your ceiling, you can operate it using the Nest app on your smartphone, tablet, or smartwatch. If the detector senses smoke or carbon monoxide, it alerts you with a female voice at 70 decibels. This voice will tell you exactly where in the house there is danger. The app also keeps you updated on the battery status and sensor functionality. By connecting the Google Nest Protect V2 via Wi-Fi to other Google Nest products like the Google Nest Thermostat and the Google Nest IP Camera, you gain additional benefits from each product. The green light turns on as soon as the motion sensor detects movement in the dark. The Google Nest Protect V2 (Battery) operates with 6 AA batteries, which are included by default.