Perfluoroelastomer (evolast® FFKM) is the highest-performing sealing elastomer available, combining chemical resistance approaching that of PTFE with the elastic recovery of a rubber. It withstands nearly all chemicals, including solvents, acids, bases, amines, and steam, with grades rated for continuous service to 600°F (316°C) and beyond. Moss Seal supplies evolast® FFKM for semiconductor plasma and wet process equipment, aggressive chemical processing, and critical oil and gas applications where a single seal failure is unacceptable. The material carries a significant cost premium over FKM, so it is specified where the fluid, temperature, or consequence of failure genuinely rules out every other compound, and grade selection is matched to the specific process chemistry.