Perfluoroelastomers (FFKM) are mainly synthesized from tetrafluoroethylene, perfluoromethyl vinyl ether,and vulcanization point monomers, and have excellent resistance to chemical, heat, extrusion, and high-temperature compression deformation. Except for certain high fluorocarbon solvents,they are not affected by any medium,including ethers, ketones, esters, amides,nitriles, strong oxidizing agents, fuels, acids, alkalis, etc. It has low permeability to chemicals and gases, and good electrical properties.