Gree is the world's largest air conditioning manufacturer and one of the pioneers in using inverter technology for low energy consumption air conditioners. In DC Invertor airconditioners, the motor of an inverter compressor has a variable speed, unlike a non-invertor compressor, where the speed is fixed and thus operates always at full speed. By enabling variable speed, inverter air conditioners ramp torque up slowly and minimize energy consumption. Gree air conditioners come in both wall mount split and floor standing models with tonnage covering 12000 BTU (1 ton), 18000 BTU (1.5 ton), 24000 BTU (2 ton), and 48000 BTU (4 ton). Air conditioner models come in both heat and cool and cool only varieties.