EPDM  - ETHYLENE PROPYLENE DIENE MONOMER 

EPDM is a terpolymer elastomer made from ethylene-propylene diene monomer. The M refers to its classification in ASTM standard D-1418
It offers excellent resistance to polar fluids such as water, phosphate esthers, and ketones but is not recommended for petroleum oils and solvents. EPDM possesses excellent resistance to heat degradation, compression set, low temperatures, sunlight, ozone, weathering, abrasion, and tear resistance. It has excellent electrical insulating properties.  The effective temperature range is -70ºF to +300ºF.