HCFC (Hydrochlorofluorocarbons) is an alternative to CFC, whose ODP (Ozone Depleting Potential) is low. It mainly includes R22, R141b, R142b, R406A, R408A, R123, etc. The ozone layer destruction coefficient is only a few percent of R11. Therefore, HCFC substances are currently regarded as the most important transitional substitutes for CFC substances. In the Montreal Protocol, R123 is limited to 2030.