Ductless mini-split: outdoor compressor + indoor air handler connected by refrigerant line set (3/8 liquid, 5/8 suction for 12K BTU). Capacity: 12,000 BTU/hr (1 ton). SEER2: 20-42 (inverter-driven). HSPF2: 10-15. Heating capacity: rated to -13F to -22F (cold-climate models: Mitsubishi Hyper-Heat, Fujitsu XLTH, LG Red). Refrigerant: R-410A or R-32. Installation: mount indoor unit high on wall (7ft+), line set through 3in core hole, outdoor unit on pad or bracket. Electrical: dedicated 20A/240V circuit. Condensate: gravity drain or mini pump. Multi-zone: 2-8 indoor units per outdoor unit. Cost: $3,000-$6,000 installed (single zone). ENERGY STAR certified models available. Ideal for: additions, converted garages, rooms without duct access, supplemental heating/cooling. CSI 23 81 26.