Emerson 1E56N-444 LOW VOLTAGE THERMOSTAT, TERMINAL DESIGNA

Low Voltage Thermostat, Terminal Designations A, B, G, O, Rc, Rh, W, Y, System Switching Heat-Cool-Off, Fan Switching Auto-On, Dual Transformer Compatible Yes, Power Method Hardwired, Voltage 20 To 30V Ac, 750Mv Compatible Yes, Mounting Vertical, Height 4 1/2 In, Width 3 1/4 In, Depth 1 5/8 In, Color White, Control Range 50 Degrees To 90 Degrees F, Features Mercury Free, For Use With Heating, Cooling, Heat Pump Without Auxiliary Heat, Millivolt, 3-Wire Zone Valve