The Honeywell Wifi Thermostat THX9421R5021WW with THM5421R02 is a programmable digital thermostat that offers convenient control through Wi-Fi connectivity. This thermostat allows users to easily adjust the temperature settings in their homes from anywhere, making it a convenient and energy-efficient choice for home heating and cooling systems. With its reliable brand reputation and advanced features, this thermostat provides a comfortable and efficient way to regulate the temperature in your home. This two wire thermostat with equipment interface module was replaced when a new system was installed but is in good working condition.  Ships with the fastest service available.