The Honeywell YTHX9321R5003 Prestige HD Comfort System Kit is an advanced thermostat and control solution designed for compatible residential HVAC systems. It monitors indoor temperature and system conditions, then communicates with connected heating and cooling equipment to maintain the selected comfort settings. Suitable for compatible furnaces, air conditioners, heat pumps, and oth... https://www.partshnc.com/ythx9321r5003-honeywell-prestige-hd-comfort-system-kit