A utility prop for magicians, with many diverse applications. A more sophisticated version of the bottomless glass, this permits you to "prove it is a regular glass" by some subtle handling. You can pour liquid into or out of this.
The magician asks a spectator to choose a card; it is put back in the deck and this is placed on the table. The spectator is then asked to rest his finger on the top of the deck. Suddenly, right under his finger a "magical force" separates the deck into two... exactly where the chosen card is!
The magician borrows some rings from the audience and chains 3 of them together, showing them to the audience; incredibly the rings are loosened and given back to their owners safe and sound. Nobody will be able to find out the secret.