The vortex tube, also known as the Ranque-Hilsch vortex tube, is a mechanical device that separates a compressed gas into hot and cold streams. The gas emerging from the hot end can reach temperatures of 200 °C (390 °F), and the gas emerging from the cold end can reach −50 °C (−60 °F). It has no moving parts and is considered an environmentally friendly technology because it can work solely on compressed air and does not use Freon. Its efficiency is low, however, counteracting its other environmental advantages.