Ethylene-propylene-diene rubber (EP rubber) is a polymer made of ethylene, propylene and a small proportion of a diene. The distinctive characteristics of this material are: very good resistance to ageing, weathering and ozone; good resistance to swelling in hot water, steam, washing lyes, oxidizing media, brake fluids and many acids and bases. Severe swelling in practically all hydrocarbons prohibits use of mineral oil products even as assembly aids. If it is essential to lubricate EP parts, suds or silicon grease and oil may be used. According to manufacturers' specifications the thermal range of application extends from -55 °C to +140 °C, and with special "hot water blends" up to + 150 °C and +180 °C in an inert environment.