Easy Programmable mode ensures the desired temperature is reached by the programmed time, making for a comfortable home whenever you need it. Separate 5-day (weekday) and 2-day (Saturday/Sunday) programming with four separate time/temperature periods per day,to reduce energy usage,savings on annual heating and cooling costs. Easy to read in large dispay,OPTIONAL 2 “AAA” Batteries provide continuous temperature display during power loss.Low Battery Indicator available.?IMPORTANT? Currently does not support millivolt systems Compressor short cycling protection,1 heating, 1 cooling and heat pumps without auxiliary heat, Does not work with electric baseboard heat (120-240V).Detailed instructions for easy installation,C-wire needed for proper installation. Note-c wire is required and is the primary power source for your thermostat. Without a c wire, your thermostat will not power up?In the case of battery power, there is no need to connect the C wire. Accurate temperature control of +/-1-Degree F for consistent comfort, Detailed instructions for easy installation, 12 or 24 hour clock.