A person chooses a card their card is placed back in the deck. you then take out a large paper clip and show a card of a different color than their card is inside the paper clip. that card then instantly changes color to match the color of their card. you then remove the card from the paper clip and show them that it is their card. this is a visual color change that happens while the card is held securely by a paperclip. easy to perform and create.