Piloted Check Valve Hgl-M5-QS-4 with Sealing Ring Ol, with Qs Push-In Fitting. Valve Function=Piloted Non-Return Function, Pneumatic Connection, Port 1=Qs-4, Pneumatic Connection, Port 2=M5, Type of Actuation=Pneumatic, Pilot Air Port 21=Qs-4, Festo