Return air sensor. Mount on return duct for backup control of non-zoned RedLINK™ enabled wireless systems and thermostats. Works with THM5320R1000 equipment interface module to maintain safe indoor temperatures if power is lost at wireless thermostat. Takes control of equipment by turning on blower fan and sensing indoor temperature. Controls heating at 62F and cooling at 82F. Provides homeowners with peace of mind. Installs in minutes.