They come in six models with varying footprints and capacities ranging from the 15.75 × 7.50 × 6.30-in. 800 Btu T15 for wall-mount enclosures or enclosures with narrow sidewalls, to the 52.85 × 20.85 × 13-in. 20,000 Btu T53. Each model maintains a UL/cUL Type-4 rating. These closed-loop airconditioning systems maintain a UL50-rated separation of the external ambient airflow from the sealed cabinet interior. All models carry a head pressure control for low ambient operation, a compressor heater, coated condenser coil and thermostat, and use environment-friendly refrigerant.