'Butterfly rollovers' is the term Bally gave to the switches located in the large horseshoe lane surrounding the pop bumpers. According to Bally's parts catalog, Early Production games for Grand Tour had their steel back doors mount directly into a wood groove in the backbox but during production a steel retainer was installed into the wood groove for the rest of the production run. The Add-A-Ball version of this game is Bally's 1964 'Happy Tour'.