Ethylene-propylene rubber is a versatile, economical compound that functions well in both high and low operating temperature environments. It has moderate to good resistance to a variety of chemicals, making it a popular compound for a variety of applications. Because of EPDM's chemically saturated polymer chain, it has superior resistance to degradation. However, its use is limited due to its incompatibility with petroleum based fluids. EPDM can be cured with sulfur or peroxide, although peroxide cured compounds should be used in applications with high heat requirements. Peroxide curing also produces vulcanizates with better compression set than sulfur cures. Due to its lack of gum strength, reinforcing agents are extremely important in ethylene-propylene polymers. As a result, high tensile and tear properties are attained through high loading. EPDM is a terpolymer, not to be confused with the copolymer EPM, which due to its completely saturated polymer backbone, can only be peroxide cured.