The performer borrows a coin, which can be marked. It is covered by a handkerchief, and given to a spectator to hold. 

He now removes from his pocket a plastic box, which is placed on the table, or given to another spectator to hold.

The handkerchief is whipped away – the coin has vanished. 

The spectator holding the box is asked to open it. Inside is another plastic box. And inside that a third. And then a fourth !

And finally inside the fourth plastic box is the same marked and borrowed coin.

The trick is almost automatic in working – thanks to a very special gimmick supplied with them.