The cup is more flexible than a force cup plunger and will increase the suction effect. For maximum effect, with a tight seal and no air in the cup, a back and forth motion will create high and low pressure at the point of the blockage. Buffalo Plungers are strong powerful and get the job done! Can be used across sinks, baths, drains, toilets and even showers. There is a complete range of plungers in the buffalo range that work across multiple applications.