Digital 2 Heat/1 Cool. Easy to read green backlit display. Precise temperature control of +/- 1 F (degree fahrenheit). Green backlight. Early start function adjusts the pre-heating/cooling. For use with central gas, oil, electric furnaces and air conditioning. Works with millivolt systems. For heat pumps with our without aux heat. Basic operation keeps programming simple, and installation requires 15 minutes or less. Includes mounting hardware.