2 Lithium ion batteries required.

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ENERGY STAR CERTIFIED. See your energy use in the Monthly Energy Report, and help save even more with a schedule that adapts to your lifestyle, and by connecting with your utility efficiency program (rebate finder link above).EFFICIENCY AND REWARDS. Connect your Honeywell Home account with your utility to earn rewards each season for your energy efficiency.Before purchasing, check to see if this thermostat is compatible with your home and to determine if your home needs a C-wire power adapter.Works with most heat/cool oil furnace systems. Will not work with heating only oil furnace systems unless a C-Wire is present.
AUTO HOME AND AWAY MODE. Adjust your thermostat from anywhere with your mobile device, or let your home automatically react to your schedule with geofencing