This easy-to-use electronic thermostat saves three temperature settings and is millivolt compatible. For use with the Sensaphone or FreezeAlarm Deluxe, eliminates the need for two thermostats to operate the "setback" and "warm-up" features of the Sensaphone and FreezeAlarm Deluxe. Please note: Power Supply (500ma Adapter) is required for this unit. TH135 APPLICATIONS: Oil Burner, Natural Gas, Hot water heating, Hot air system with no ventilation control, Millivolts system, Electric heating with relay