An FEP O-ring is a type of O-ring made from a fluorinated ethylene propylene (FEP) material. O-rings are sealing devices used in a variety of applications to prevent the leakage of liquids or gases between two mating surfaces. FEP is a synthetic polymer that has excellent chemical resistance, high-temperature resistance, and electrical insulating properties. FEP O-rings are often used in applications where resistance to harsh chemicals, high temperatures, and electrical insulation are required.