5 Day/2 day, 5-1-1 day or 7 day programmable multi stage heat pump thermostat. Blue back light. Filter Monitor. AC powered with non-volatile. settings-no batteries required. Refresh programmable fan mode. Residual cooling fan delay, user selectable. Adjustable 1st and 2nd stage span adjustment. Staging timer. Heat/Cool auto cutoff. Bi-metal freeze protection. Pre-Programmed. Easy Front Load battery case. Latching relay outputs. Most Compatible With Two-stage heat pumps with 2 heat/2 cool, gas or electric auxiliary heat Two-stage heat pumps with 2 heat/1 cool, gas or electric auxiliary heat Single-stage heat pumps Not for use with 110V/220V systems. Terminations: R, B, W2, E, G,O, Y2, Y1, L, C. 5 Day/2 Day, 5-1-1 Day or 7 Day programmable multi stage heat pump thermostat. Latching relays for system compatibility. Soft touch keypad. Low battery indicator. Indiglo Backlight. Easy, front load battery access. 2 AA batteries included. Are compatible with: 24 VAC heat/cool, Heat only or cool only systems. gas, electric or oil systems, millivolt systems, 2 wire hydronic systems (Not for use with 110/220V systems). Have These Specifications: 20-30 VAC, 50/60 Hz, Current draws 0.1 to 1.5 amps, Temperature set range: 45 - 95 degrees Fahrenheit. Operating differential +/- 1 degrees Fahrenheit. Compressor protection: 4 min. delay on break. 3 year warranty.