This pair of industrial suction cups, also known as Magdeburg Hemispheres, features 3.25" diameter rubber cups with handles and release stubs. Each half is 2" tall with 1" finger holes. When suctioned together, a minimum of 100 Newtons (22 lbs) of force is required to separate them. The apparatus demonstrates the force of air pressure without requiring a vacuum pump. Students place the edges together, squeeze out the air, and attempt to pull them apart in a tug-of-war format. A single cup stuck to a flat, smooth surface requires up to 26 lbs of force to remove at maximum adhesion.