Invented by El Duco

No, this is not about Penn & Teller. It's a novel close-up effect from El Duco!
Ask a spectator to shuffle the deck and count off 12 cards. He chooses one and you give him your pen to sign the card at the face. You don't see which card he has selected. Put the card back into the packet and ask the spectator to shuffle once more.
He places the 12 cards face down on the table like a clock. Now you place the pen, supported by a gleaming brass weight, in the middle of the card clock. It's the hand of the clock, you explain.
Show that the hand can be moved in both directions around the clock. Now you ask the spectator to slowly move the pen with his finger around the clock.
SUDDENLY THE PEN STOPS! YOU CAN'T MOVE IT FURTHER. THE PEN POINTS TO ONE CARD. THE SPECTATOR TURNS OVER THE CARD - IT IS HIS SIGNED CARD!
The spectator does everything himself. He selects the cards, he shuffles and places the cards in any order he wants and he moves the pen until it stops pointing at his signed card!

PLEASE NOTE:
- No force is involved
- No magnets, threads or electronic device.
- Everything can be examined.
- Do it in any place at any time with different results.
- No reset El Duco's PEN - TELL uses a very simple but unique principle. The trick is very easy to perform. Comes complete with everything you need, but the deck.