Nut and Bolt Mystery

Three cards are show with pictures of a colored bolt on each one. The cards are turned around and mixed. The spectator selects one card but does not show it. Then the three bolts are put in the bottle and the cap is placed on the bottle. The bolts are spun around in the bottle. You the open the bottle and dump the bolts out. Notice that the nut is off one of the bolts. When the selected card is turned over it matches the bolt with the off. Great trick that can be repeated. They say people go nuts over this effect