Shocking prediction - great prediction card trick revealed

Preparation is very easy - take any two playing cards and glue them together back to back (or use piece of double sided tape).

Place this card into envelope and leave it on the table.

You must remember your selected playing cards and their position in the envelope (whether its facing up or down).

Then you will need duplicates to cards you used for creating the gimmick.

Take three playing cards and introduce them to spectator - remember that two of them must match your prediction (gimmick you prepared)
Tell him that you have also prediction prepared inside the envelope
Let the spectator to choose any card - they are facing up and its trully a free choice
Once spectator select the card (you can offer him to change his mind if he wants), take the envelope with the prediction and pull out your card that will match his selection - this will be possible due to the fact that you remember how you placed your prediction inside the envelope
If spectator selects card that is not in the envlope, simply ask him to choose another card so you will be always left with card that you have prepared as prediction

Shocking prediction - great card trick revealed