Black Fluorocarbon O ring, also known as a Viton o-ring or FKM, FPM orings. FKM (Viton ®) O’Rings have a low compression set and have high temperature and chemical resistance with Durometer / Shore A 90 which use for high pressure. For normal pressure you can use O-Ring Viton shore 75 .
The terms FPM, FKM and Viton® very often cause confusion and lead to incorrect interpretations. All of these designations actually stand for one single base material: fluoro rubber.