PTFE piston seals are available in various shapes and compounds. The selection should be made on the basis of pressure,Website:http://www.rayflon-seals.com, temperature, and the type of air or fluid medium in which the cup must function.Material include: Virgin PTFE, POB filled PTFE, PI (Polyimide) filled PTFE, Bronze filled PTFE, and others as request.Virgin PTFE piston seals is suitable for middle and low pressure applications which no need fillers to reinforced. Properties:Good chemical resistance Low friction Wide temperature using range Long service life