The Panasonic CSS22NKU1 is a single zone air handler and requires a Panasonic CUS22NKU1 air handler to operate. The Panasonic CSS22NKU1, 21,000 BTU Ductless MiniSplit WallMounted Cool Only Air Conditioner (Indoor Unit). The Panasonic's Ductless Split Air Conditioner products give you the perfect solution in refreshing and cooling the air in your apartment. The Panasonic's 21,000 Indoor unit (evaporator) saves your space as it is enclosed in a beautiful cabinet and attached inside the room. The Indoor unit is affixed to the outdoor unit (condenser) via refrigerant lines interunit wiring through a 31/2" opening in the wall, the installation is elementary, fast and efficient as there is no ductwork needed. The Panasonic CSS22NKU1 Indoor unit's remarkable design offers you Whisper Quiet operation. The Panasonic MiniSplit Ceiling Recessed Air Conditioner offers you not only the elegant design and whisper quiet operations, but also the quality and reliability you can count on.