From the Manufacturer

DERNORD True Union Ball Check Valves prevent reversal of flow in tubing systems. Line pressure moves the solid plastic ball off the elastomer seat, opening the valve. When the inlet flow stops, back pressure moves the ball back onto the seat - stopping the flow. UPVC union check valves must be used in an upflow position to work properly. Check valves must be installed with the valve's flow arrow pointing in the direction of the flow. Do not install valve upside down. True union check valve, can be taken apart for cleaning, allows for easy removal without breaking down the piping connection. （NOTE: NO SPRING) The UPVC check valve is low-temperature-resistant, impact-resistance, rust-resistance. It is ideal for flow control, such as commercial plumbing, aquariums, irrigation, swimming pools, water parks and OEM applications.

Size: 1 inch socket