Take a pen and stick it through the Invisible Zone case. The pen goes in one side and comes right out the other. When you open the case, the center of the pen is totally gone, replaced by a metal spring.
A very clever trick from the great mind Lubor Fiedler. I perfer to remove the spring as I cant see the point of the middle of the pen changing to a spring, having the middle vanish now that's a miracle. A brilliant trick for under $20.00
