Maxello Magic

The magician shows two decks of cards in their boxes, one red, one blue. One of the decks is chosen and in an instant the box disappears, leaving the cards in his hand.

The magician takes the box from his pocket showing it traveled there. Showing the cards face and back, tosses them on the table, the backs change color in a second! When the other box is opened, the deck of the chosen color is in it!