Viton® is also known as: Fluorocarbon and FKM.  

A fluoroelastomer compound with a combination of exceptional mechanical properties and compression set resistance. This particular energizer gives an O-ring excellent memory and the ability to recover rapidly from deformation. This core has a Shore A hardness of 75 with a suggested operating temperature range of -10°F to +300°F (-23°C to +150°C) in encapsulated applications.

Viton® is a registered trademarks of DuPont® Dow Elastomers.