The Jones Stephens B04400 is a 4" backwater valve that helps reduce backflow in your drainage system. Its cover comes threaded for easy inspection and it has an elastomeric gasket to ensure watertight seal which prevents any leakage from the valve. Also, the PVC (Polyvinyl Chloride) construction of this backwater valve will contribute many performance advantages with its lightweight feature and good mechanical strength that can withstand destructive elements over a long period of time. This backflow valve is NSF-approved, having met the public health and safety standards. Jones Stephens will continue to provide reliable products, like this B04400, that will meet your needs without costing a fortune.