For multi-stage heat pump/conventional two-stage heat/cool thermostat with auto season changeover. Energy monitor. Filter monitor. No programming required. System on indicators. Keyboard lock. Auto heat recovery. AC powered with 2 AAA battery backup. Optional hardwire remote sensors. Compatible with most: Two-stage heat pumps with 2 heat/2 cool. Two-stage heat pumps with 2 heat/1 cool. Single-stage heat pumps. Display temperature limits: 40 - 95 degrees Fahrenheit. Terminations: R, Y1, Y2, W1,W2, E, O, B, G, L, C. Remote sensor terminations: RS1+, RS1-, RS2+, RS2-, Conventional two-stage heat/ cool systems (not for use with 110v/220v systems). Multi-stage heat/cool. Latching relays for system compatibility. Soft touch keypad. Low battery indicator. Indiglo Backlight. Easy, front load battery access. Temperature set range: 45 - 95 degrees Fahrenheit. Operating differential +/- 1 degrees Fahrenheit. Operating differential +/- 1 degrees Fahrenheit. Compressor protection: 4 min. delay on break. 3 year warranty.