The magician shows a coin on his left hand. At this point, passes the right hand over the coin and this will turn into another of a different value. After the game, since the coin is completely normal, it can be made to control the spectators.
A change very visual.
This coin is an accessory, to be used you will need a magnet or a magnetic card from the game.
The video showed the effect, but the value of money that you will receive is the one shown in the description and photos.