Marked ESP Cards
Good quality ESP cards - all black symbols, and the cards are marked as well, easy to read but not obvious for people looking them over.
A simple trick is explained in the instructions as well.
Here's the blurb...
ESP cards were developed and introduced by Dr. J. B. Rhine of Duke University for the purpose of testing for Extrasensory Perception. They consist of five basic symbols: Circle, Cross, Wavy Lines, Square, and Star.
It is very easy to remember these symbols by using a quick and easy numbering system. A circle is one continuous line. A cross is two lines. There are three wavy lines in the third symbol. A square has four lines. The star used has five points. This deck consists of twenty-five cards, five cards of each design.
There are many effects that can be performed with this deck of cards. For example:
Here is a simple, yet amazing effect that is direct and to the point. You and a spectator each choose a card in the fairest possible manner. When the two cards are revealed. They match. Proving to the audience that, yes, you do have ESP.