Program each day differently - up to 4 periods per day. Energy Savings - Program to save up to 33% on annual heating and cooling costs (if used as directed. Savings may vary depending on geographic region and usage). Basic operation keeps programming simple. Backlit display. early start function; precise temperature control of (± 1-degree F) for maximum comfort. Display Options - degree C or degree F temperature - 12 or 24 hour clock. Compatible with heating and cooling plus heat pump systems. Does notwork with electric baseboard heat (120-240V) and multi-stage heating/cooling systems.