Low Voltage Thermostat, Terminal Designations B, G, O, R, RC, W, Y, System Switching Heat-Cool-Off, Fan Switching Auto-On, Automatic Changeover No, Dual Transformer Compatible Yes, Power Method Hardwired, Voltage 20 to 30V AC, 750mV Compatible No, Mounting Horizontal, Height 2 27/32 in, Width 4 23/32 in, Depth 1 1/2 in, Color White, Control Range 50 Degrees to 90 Degrees F, Features Mercury Free, For Use With Gas, Oil, Forced Warm Air, Hot Water, Steam or Gravity, Includes Dealer Logo Pocket