7 day programmable or non-programmable thermostat, unique program for every day of the week. user option: 2 or 4 periods per day, temporary override and manual hold, programmable keyboard lock, speed slide for easy programming, selectable fahrenheit/celsius setting, adjustable temperature swing (differential), adjustable 2nd stage heat offset, programmable air filter life timer monitor, easy-view large back-lit display, energy use monitor, selectable smart recovery, easy to use, easy installation, dual powered (2aa alkaline batteries- not included). for use on: universal compatibility for conventional heat & a/c up to 2-stage heat/2-stage cool, for heat pumps with up to 2-stage heat/1 stage cool, 3-wire heat only hydronic systems (hot water) zone valves, & gas millivolt heaters