Two packs of face down cards are shown to be 4 Red Backed and 4 Blue Backed, all face down. The magician tells the helper that the cards are all Jacks and the spectator can name any two of the four suits, Hearts, Clubs, Spades or Diamonds as long as they pick one of each color. For the first climax, the cards are spread and just the named suits are the only face up card in each pack.
For the second climax, the magician tells the helper that he will make them switch places and to prove it, when the cards are pulled from the packets and turned face down, the spectator can see that each face up card has cleanly changed places because the cards have different color backs than the packet that they came from.
As third and final climax, the spectators' thought-of cards prove to be the only cards that would make the trick work because all the other cards in both packets are blank.