On one side is the rebus and a blank area where the address or name of the recipient can be written. The other side has the show details on it, as well as the answer to the rebus. This means that the card can be folded in half and glued around the perforated edges, prior to posting, so that the recipient can only see the rebus and their own name. To open the card they have to tear off the edge at the perforations, so revealing the details of the show and the answer to the rebus. Have a go at solving the rebus before you click on View Details.
This is a reproduction poster made in 2000 from the original which was then in the Nielsen Collection.