So the Mitsubishi PUY-A42NHA6 is 42,000 BTU, but it just has 14.4 SEER efficiency.
Reviewing the specifications of Mitsubishi air conditioners is made easier by dividing the equipment into outdoor units (condensing units) and indoor units. Then it carries it outside and disperses it through a radiator-type coil, effectively cooling the air indoors. Refrigerant is carried from the condensing unit to the indoor unit where it captures heat. Each indoor unit cools a single room or zone. The AC-only systems include an outdoor condensing unit and one indoor unit installed on the floor, wall or ceiling.
These split systems are often called mini-split systems because both the outdoor condensing units and indoor air handlers are smaller than those of standard ducted split system components. Mitsubishi remains the world leader in ductless systems. Mitsubishi Air Conditioners Brand Overview