Remote outdoor temperature sensor, when installed, the current outdoor temperature is displayed. Also can be used to manage dual fuel and lock-out expensive auxiliary heat in heat pump applications.
PRO® Series Thermostats
Remote Temperature Sensors
Honeywell Remote Sensor, Series: C7089, -40 to 120 deg F, 5 to 95 % Humidity, 2-1/4 x 3/8 in, Import