An exercise in visual simplicity. As stunning as card tricks can get, and as simple to perform as you could wish.
Effect: You show the audience two boxes of cards, a red back and a blue back. But when you remove the cards from the boxes there seems to have been some mistake! The red cards are in the blue box and vice versa. The audience clearly sees the color of the cards. You place the cards back into their (wrong) boxes and with a wave of your hands cause them to change places. They are now back in the correct boxes! This one really leaves the audience stunned.
No sleights. Packs in full view all the time.