Canplas 223283W PVC Backwater Valve, 3-Inch Protects basements and other low level areas from the backflow of sanitary sewer, storm sewer, or septic system Easily fits and this is easy to install Made in United States Protection against the backflow of sewage and storm water Compact, lightweight and easy to install All Canplas Backwater valves are socket x socket with all sockets being DWV Acme threads provide positive traction and extra strength Neoprene O-ring effectively seals valve lid