Astor Mental by Astor - TrickEffect For this trick the magician uses a transparent perspex board, five E. S. P. cards with blue back and five E. S. P. cards with red back. Every blue backed card has its matching red backed card. You will have the same E. S. P. symbols on the faces of these cards. The magician slips the blue cards into their slots on the board in an order only he knows. The spectator chooses one by one, in which matching slot the red cards should go, but he only