4 '', PVC backwater valve, sewage or any otherwise fluid from flowing plunk for into a water system, elastomeric seal in ready action flapper ensures a water seaworthy seal, rib access cap incorporates a neoprene seal for incontrovertible sealing & can be tightened or removed by hand, valve hub fits dwv pipe & can be adapted for sewer & drain pipe. The product is in china. Easy and light handling.