Automotive air-conditioning systems use rubbers in seals around the fittings and shafts, and in hoses that conduct both gaseous and liquid refrigerants. Halobutyl Rubber X_Butyl® is considered by many air-conditioning hose manufacturers as the base polymer for this application, because of their excellent permeation resistance to the refrigerant R-134a, high damping of low frequency vibrations, excellent low temperature properties and excellent heat ageing. The vulcanizates based on halogenated X_Butyl®, when correctly compounded, meets the most stringent specification requirements and prevent the ingression of moisture into the air conditioning system.