For years, processability of compounds has generally been improved through use of plasticizing oils and process aids. In many cases this solution has been inexpensive and easy to implement. However, in some applications, the use of these materials can have deleterious effects, necessitating the use of a compound with little or no plasticizer, which subsequently has poor processing characteristics. This is especially true when compounding for very demanding EPM or EPDM applications. Attempts are sometimes made to use the lowest possible viscosity EPM or EPDM reactor grade, but that often results in a difficult balancing game between attainment of mechanical properties and acceptable processability. Several unique ingredients have been introduced to the rubber market to provide a viable solution, but many are in liquid form, and as such are difficult for mixing plants to handle; can have compatibility problems with EPM or EPDM; and can be cost prohibitive. In 2008, DSM Elastomers installed a state of the art reactive extrusion (REX) line in Triunfo, Brazil. The technology provides a route to manufacture ultra low viscosity EPM and EPDM. In this paper, Keltan