Honeywell Mercury Free Round Thermostat, 18-30Vac, Battery Assisted Power Stealing, 40-90 Degree Temperature Setting Range, 1 Stage Heat, 1 Stage Cool Conventioanl Systems or Heat Pumps with No Auxiliary Heat, Heat-Off-Cool System Switching, Auto-On Fan Switching, Thermistor Sensor Element, 1 Degree Accuracy, 5-90% RH Non Condensong Operating Humidity Range, Premier White