The Honeywell THX321WFS2001W T10 Pro Smart Thermostat with Red LINK Room Sensor is a Wi-Fi enabled thermostat for smart home integration. It allows remote control of your HVAC system's heating and cooling functions from your smartphone or tablet. Beyond basic scheduling, it can use temperature readings from the included Red LINK Room Sensor to prioritize comfort in specific areas of your home. This can improve comfort and potentially reduce energy consumption by focusing on occupied spaces. The compact thermostat measures 4.5 inches by 3.5 inches by 1 inch and operates on a safe, low-voltage of 24V.