The Google Nest Temperature Sensors allow you to maintain a comfortable temperature in any room of your house. They work by sensing and communicating the temperature in a room to compatible Google Nest thermostats. Equipped with Bluetooth Low Energy wireless technology. A working range of up to 50' away from your Nest Thermostat. Includes a CR2 3V lithium batteries deliver up to 2 years of battery life. The free Nest app allows for simple setup and customization.