Most commonly known as AFLAS® or Viton® Extreme™; Tetrafluoroethylene Propylene (FEPM or TFE/P) is a fluorinated rubber. It has excellent resistance to a wide variety of chemicals, both acids and bases. It works well at elevated temperatures and has very good resistance to petroleum fluids. AFLAS® has excellent steam and hot water resistance.

The raw material cost for FEPM is relatively high and it is difficult to process. Like most other fluoropolymers, FEPM does not have especially good low temperature properties

The temperature range for FEPM compounds is 0º to 475º F (-15 to 245ºC). PAI offers FEPM compounds in a hardness range of 70 to 90 durometer. Black is the standard color, but some others are available.