ISO 16589 specifies seals utilizing sealing elements manufactured from suitably formulated compounds based on thermoplastic materials, such as polytetrafluoroethylene (PTFE). They are considered suitable for use under low-pressure conditions. ISO 16589-1:2011 shows seal types and examples. It also specifies the nominal dimensions and tolerance of the seals, shafts and housings, as well as a dimensional identification code.