In 1945, Kellogg's inserted a prize in the form of pin-back buttons into each box of Pep cereal. Pep pins have included U.S. Army squadrons as well as characters from newspaper comics and were available through 1947. There were five series of comic characters and 18 different buttons in each set, with a total of 90 in the collection. Other manufacturers of major brands of cereal, including General Mills, Malt-O-Meal, Nestlé, Post Foods, and Quaker Oats, followed suit and inserted prizes into boxes of cereal to promote sales and brand loyalty.