"Imagine that the little card printed on the back of the deck box is the spectators!"

This effect simply put is perfectly described by the title.

You allow the spectator to select a card and then you have them sign it...
Then you place the card back in the deck or box, and ask your spectator to pay close attention to the card on the back of the deck box.
You tell the spectator that their card is actually the card on the back of the box, and in the blink of an eye you mystify your spectator and audience by removing the card from the back of the case and undoubtedly it is their card.

This Spectacular Effect come from the collaboration of two amazing magician Sebastian Calbry and John Owenn.

Strengths:
Flash Ultra
Different Versions
Easy to perform
Examinable
Super Impact
Gimmick Sly

Bonus:
Ten of Hearts