Wireless outdoor sensor measures outdoor temperature and humidity to display on RedLINK™ enabled thermostats and accessories. Powered by RedLINK™ reliability. No interference with other wireless devices in home. Reliable performance in all climates. Installs in minutes. Up to five-year battery life. Two-month low battery warning displayed on RedLINK™ enabled thermostats. Includes 2 AA lithium batteries and mounting hardware.