Matching Cards 6-Pieces

Four jumbo cards are shown each a different suit.
The cards are placed into envelopes and mixed.
No one not even the magician knows what card is in which envelope.
Four small card, mates to the jumbo cards, are shown.
These cards are placed into the envelope the spectator wishes.
Each envelope is open and the cards inside match.
No forcing the card or envelop.
Complete free choice throughout the routine.
Special jumbo cards do all the work.