resideo Low Voltage Thermostat, 20/30 VAC, 50/60 Hz Frequency, Changeover: Manual, 2 Stages, Switch Position: Heat-Off-Cool System, Auto-On Fan, Relay Switch, Analog Display, 40 to 90 deg F Settings, 5 to 90 % Humidity, Lithium Battery, Hardwired Connection, Cool Current: 0.02 to 1 A, Cycles per Hour: 1, 3, 5, 9 cph Adjustable, +/-2 deg F Accuracy, Heat Current: 0.02 to 1 A, Battery Power Source, Dimensions: 3-11/16 in Dia x 1-3/4 in D, Premier White, For Use With: 1 Heat/1 Cool Conventional Systems and Heat Pumps with No Auxiliary Heat