Ductless mini-split air conditioners provide zoned cooling and heating using an outdoor condensing unit and one or more indoor air handlers. The condenser connects to the air handlers via refrigerant line sets, eliminating the dust buildup and energy loss associated with ducted central air conditioners. Also called ductless split systems, mini splits are typically used in climates with mild winters and most commonly used in homes. They can also provide primary, supplemental, or room-specific air conditioning in office buildings, schools, correctional facilities, factories, and other commercial and industrial settings. Single-zone systems have one condenser and one air handler for conditioning a single room. Multizone systems can be configured with one condenser sized for up to four air handlers for conditioning multiple rooms.