The Magdeburg Hemisphere is a modern take on the famous 17th century experiment. With the Magdeburg Hemisphere, you can demonstrate the force of air pressure without a vacuum pump. When the two cups are pressed together, the air is evacuated and a vacuum is created, separating the discs will be an interesting challenge for your students. This experiment is a classic in the field of teaching about vacuums. It comes as a pair of 2 discs, and includes instructions. Sold in a pack of 10 pairs.