The series 21KB thermoplastic quick coupling with a valve is designed for connecting a plastic hose with a conical seat, for a 4 x 6 mm hose with an M10 x 1 thread and for hoses made of PVDF and PE. The CHEM (FVX) version is made of PVDF; according to the manufacturer's catalogue, the maximum working pressure at 20 °C is 8 bar for the PVDF version.