Pictured in this listing is a Test Game with no serial number stamped anywhere on its cabinet. The lower playfield is different than other playfields, including the one in the manufacturer's flyer. The word "STRIKES" appears in a different place, the two blue passive bumpers do not have explanatory artwork below them, and the A-B-C inserts and arrows have their colors reversed. In addition, the "B" does not appear on the actual insert, and its arrow is longer. Until 1950, whenever manufacturers placed two flippers at the bottom of the playfield, which started with Genco's 1948 'Triple Action', the flippers were reversed from each other, often with a gap between them for one or two outlanes. Starting in 1950, flippers at the bottom of the playfield began facing each other but at first were far part from each other to allow for a turret shooter between them, such as Gottlieb's 1950 'Just 21', or to allow several outlanes between them such as Gottlieb's 1950 'Rockettes'. Spot Bowler was the first game to keep the flippers facing each other while narrowing the flipper gap to the distance most familiar on pinball machines to this day.