Drain test bungs are used to block off drainpipes to prevent the ingress of water, gases, or rodents.
They are commonly used for air or water pressure testing of newly laid or decommissioned drains and sewers.
The device consists of two steel plates with a rubber insert in between. A central wing nut is tightened to expand the rubber, creating a watertight seal inside the pipe.
The center cap can be replaced with a test nipple to allow for pressure testing with a drain test kit.