Large 5 sq. In. Backlit display, 7 day, 5-2 day or non-programmable , auto or manual changeover;Residential or commercial modes, battery operated for total installation flexibility , compatible with 2 or 3 wire hydronic zone systems. Compatibility - Conventional, Heat Pump;Auxiliary heat Fossil fuel option, programmable Fan control , R and C terminals for optional 24 volt operation;Adjustable temperature limits, multi-level keypad lockout , quick reference instruction card;