With the Gemini Split Systems™, designers choose the type of refrigeration circuit and type of compressor. Either a scroll or a semi-hermetic compressor can be chosen. For the Gemini 38 Series condensing unit, refrigerant circuits range between 6 to 40 tons for single circuits to dual circuits of 10 to 130 tons. Some of the factory-installed options are low ambient control to -20¿F/-29¿C, Enviro-Shield™ coil protection, a disconnect switch, and a convenience outlet. Also offered are the Gemini 40RM Series packaged air handlers and the Aero™ 39M Series central station air-handling units. Two software programs intended to help designers match condensing units and air handlers are available: the Commercial Splits Selection, Version 4.0; and the AHUBuilder™.