If you're familiar with the history of baseball cards, you know they really got their start as premiums in products, added to tobacco, candy, and gum. That switched after World War 2 when the gum became the premium in baseball card packs. When manufacturers started competing with Topps in the 1980s, they had to find another premium. Donruss used puzzles, Score used magic motion cards, and Upper Deck inserted 3D team logo holograms. Fleer went with stickers. Their format changed throughout the years, but one side usually contained one or more team logo stickers, while the other side had team art, trivia, or stadium photographs.