A black bag is handed to a spectator who is asked to place it over their head. They attest they can see nothing but black, no light at all. The magician then takes the bag and places it over his/her head and asks the spectator to write anything (perhaps on a large dry-erase board). The magician is able to write the exact same thing- he must have X-Ray vision!
Effect is beautifully packaged and includes complete illustrated instructions in English, French, German, Italian, and Spanish!