Standard Features - Simple programming One program runs for the entire week with 4 program periods per day - Easy to use - Basic operation keeps programming easy - Precise temperature control of +/-1 F to maximize comfort - Display Options C or F temperature 12 or 24 hour clock - Compatible with heating and cooling systems - Does not work with multi-stage heating/cooling, heat pump systems or electric baseboard heat (120-240V) - Model - RTHL221B - 1-Year Warranty