Bicycle - Invisible deck - Blue back

The magician puts a deck of cards on the table closed into the case. A spectator thinks of a card and name it. The magician takes the deck opens it in his hands and shows how a single card is turned on the back. Clearly this is the card named by the spectator.
• An effect of big impact on the public because the card is thought. The spectator can name any card in the deck.