Provides proportional integral temperature regulation for maximum comfort and efficiency. Features a fully menu driven large digital display. Offers optimization for various system types (high mass, low mass, baseboard, fan coil and cooling). Take control with the easy to program 7 day 24 hour timer utilizing 9 preset programs and the ability to program 4 additional user programs. This thermostat is capable of generating a setback signal that can be best utilized with a StatLink® module and shared with other thermostats. Optional external sensor.