This 3 in. x 4 in. PVC Hub Sewer Popper Plug features a hub-style connecting end and is compatible with cast iron pipe material. The plug can be temporary or permanent.Cleanout and relief valve,Automatic pop-up releases sewage overflow outside the house,Prevents thousands of dollars in property damages,Eliminates health hazards associated with sewage overflow,Vandal and tamper resistant center,Threaded for 3 inch or 4 inch pipe or tapped together,Constructed of white PVC,Threaded unit can be used with PVC or ABS tapped together,For cast iron pipe, use standard no hub clamp,Meets southern building code section 301.10, principle No.10