Aflas was the first commercially introduced FEPM class material. In fact, there was no FEPM designation within ASTM D1418 at the time. The novel and unique attribute of Aflas was the absence of VDF. The importance of this, specifically its remarkable resistance to high pH environments, was gradually realized by the marketplace and the material gained significant recognition. Furthermore, by applying the renowned Viton trademark, DuPont inadvertently fueled the rubber class confusion by using a primarily FKM designated trademark for their FEPM class materials. More recent literature distinguishes the DuPont FEPM grades as “Viton® Extreme™”. When discussing DuPont’s base resistant polymers, it is advisable to specify the polymer grade rather than simply the Viton trademark. Thus, you do not simply want to specify Viton® for your sour completion requiring amine corrosion inhibitors but rather ETP for the same.