A POG price guide lists estimated values for collectible milk caps used in a game popularized by the World POG Federation and the Canada Games Company during the 1990s. The game pieces consisted of discs, called pogs, that were designed to resemble milk caps.
Pogs became highly collectible when the game's popularity led to the release of a wide variety of designs. Images ranged from popular TV and movie characters, to sports and politicians. Although most pogs were produced in market-saturating quantities and are generally considered worthless, according to Complex Media, rarer pogs may have some value.
Modern pog games are based on a game that dates as far back as 17th-century Japan. A Hawaiian version gained popularity during the 1920s.