Oatey 262064 Cherne Single-Size 6-Inch Muni-Ball Underground Plugs Works in all types of pipe. Easily converts to an air test plug with use of a conversion kit. Durable natural rubber construction seals the roughest of surfaces. 8"", 10"", 12"" and 15"" plugs include two-port plug for easy use in sewer air tests. Threaded aluminum bypass. Works in all types of pipe.Threaded aluminum bypass. 8", 10", 12" and 15" plugs include two-port plug for easy use in sewer air tests Easily converts to an air test plug with use of a conversion kit. Durable natural rubber construction seals the roughest of surfaces.