Digital non-programmable thermostat with manual control for heat and cooling. offers electronic accuracy, selectable fahrenheit/celsius setting, adjustable temperature swing (differential), easy to read back-lit display, selectable save energy mode, easy to use, easy installation, battery powered (2aa alkaline batteries required- not included). for use on: most 24v heating and a/c systems, 1-heat/1-cool: gas, oil, electric or single stage heat pump systems, 2-wire heat only hydronic systems (hot water baseboard & radiator), millivolt systems (wall heaters/furnaces & gas fireplaces).