Honeywell Prestige™ 2.0 IAQ THX9421 equipment interface module, with up to 4 stages of heat and 2 stages of cool.  The thermostat connects to this equipment interface module to control temperature, humidification, dehumidification and ventilation from a single point in the home.

• Thermostat and equipment interface module work together to control temperature, humidification, dehumidification, and ventilation from one location
• Electrical range: 18 to 30VAC