Optical Wallet - Card Trick Magic

Two cards are show in a small black wallet - say the King of Hearts and the Nine of Clubs. Both are removed and placed on a spectators hand. The king is face up and the nine is face down. You claim to have a special power - the ability to make the nine pass through the king. The nine is turned over and the face of the card is completely blank! The King is turned over and the nine of clubs is now printed on the back of the King! This is highly recommended by us a great effect.