1956 Bowman was a test set for the Bowman Gum Company that was distributed in a very limited release to select the design for the 1956 set.
Prior to being purchased by Topps Gum Company in December 1955, the Bowman company was busy planning and designing the 1956 set. For market research and to select the final design for the set, 324 boys were sent a presentation folder with three different cards designs glued inside. Out of the 324 original folders sent out, less than 5 are known to exist today.
Although the 1956 set was never printed, the card designs were used later. The two-picture card design is very similar to the 1956 and 1960 Topps baseball card sets and the 1957 Topps Football set. The knothole design also appears in the 1958 Hires Root Beer baseball card set.
Keith Olbermann shared his copy of the cards to Topps executives in 2002. This led to the design of the 2003 Bowman Heritage baseball card set.