A spectator places a die with a freely selected number of spots on top into an examined opaque container, which is closed with a tight press on lid.
This is then placed into a second larger examined container which is also closed by the spectator.
The spectator then concentrates on the number of spots on top of the die. The performer correctly reveals the selected number.
Comes complete with photo illustrated colored instructions for handling. A very clever and effective mental effect, at a very affordable price.