Barberi® check valves are monodirectional devices, allowing the backflow prevention of fluid under pressure. According to the model, they are normally used in domestic water installations, booster pumps systems, heating circuits, generic industrial and agricultural water installations. Sealing is permitted through vertical forces exerted by the fluid pressure against a gasket which guarantees the seal even at very low back pressures. The valve, which avoids the fluid backflow thanks to the gravity thrust on the inner valve, shall be installed vertically. The peculiarity of this valve is the presence of a plug which, in addition of stopping the inner valve, allows to use wether the side port or the axial port.