Locking System by Craziest!

Imaging having a blue card inside of a clear envelope locked with a lock. Now the spectator selects a card from a red deck and he signs it. Now the magician put the card in the middle and he shuffled the deck. Magically the red card from the inside of the transparent envelope is the spectator's signed card.

You will receive everything ready to go:

A transparent envelope
The lock with the keys
A special gimmicked card
Video tutorial