Properly used, a plunger can produce pressure sufficient to bust clogs in sinks, tubs, and toilets. To produce sufficient pressure, it may be necessary to block adjacent drain or overflow openings with wet rags. Home Improvement Encyclopedia
Also known as Force Cup, Plumber's Helper, Plumber's Friend. Used for clearing obstructions from sink drains and toilets
A plunger (occasionally, plumber's helper) is a common device used to release stoppages in plumbing. Officially known as a "hydroforce blast cup", it consists of a rubber cup with an attached stick, usually made of wood. The cup is pushed down against the drain, and either pressed hard into the drain to force air in, or is pushed down until the rubber cup is flattened, then pulled out, causing a vacuum.