This came from an old magician’s estate. No instructions but the working is rather obvious once you have the prop in your hands. There is some light staining on the white surfaces but from a short distance it’s not really all that noticeable.
Effect: A tall cardboard plaque is shown that has three green dots and one red dot on it. The red dot is at the bottom. The magician places the plaque behind his back and then brings it back out front once again. Every time this is done the audience can see that the red dot has moved up the plaque, one dot at a time, until it reaches the top position.
The way that this is accomplished is questioned by the audience and they think they know how the magician is performing the trick and want to see the back side. But after some comedy byplay comes the unexpected finish. One side of the plaque is shown to now have all green dots and the other side is all red!