Weekday/Weekend Programming - One Program For The Weekdays And A Separate Program For The Weekends With 4 Program Periods Per Day. Basic Operation Keeps Programming Easy. Precise Temperature Control Of +/-1 Degree F To Maximize Comfort. Works With Heating And Cooling Systems Plus Heat Pumps Without Back-Up Heat. Does Not Work With Heat Pump Systems With Back-Up Heat, Multi-Stage Heating/Cooling Systems And Electric Baseboard Heat (120-240V).