The contractor's non-programmable thermostat choice for 1H/1C systems. Can mount horizontally or vertically. Easy installation, easy to view large back-lit display and adjustable compressor delay. Additional features include user temperature calibration in both Fahrenheit or Celsius, adjustable 9-step temperature swing and high and low limits. Low battery indicator. Dual powered 24 VAC or (2AA) Alkaline Batteries (included) with low battery indicator. Compatible with most 24V heating and A/C systems, 1 heat/ 1 cool and single stage heat pumps, 2-wire hydronic, hydronic air handling systems, millivolt systems (wall heaters/furnaces, gas fireplaces and/or pellet stoves). Not compatible with multi-stage gas heat pumps, gas or oil furnaces, 3-wire hydronic systems, 120/240V line voltage systems (without transformer). 5 year limited warranty.