These inflatable blocking plugs with a bypass have a rubber bladder that inserts into a pipeline and fills with fluid to provide a temporary plug to block flow. The bypass is a removable cap that allows flow around the plug and helps release and clean out material that may have accumulated inside the pipe. They fit out-of-round pipes that have lost their shape due to wear or damage. They are primarily used in drain, waste, and vent (DWV) systems, and underground sewer lines for maintenance and testing of water systems.