The 1990s revival is credited to Blossom Galbiso, a teacher and guidance counselor who taught at Waialua Elementary School in Oahu.
Seven other companies entered the milk cap field after a comic book and card industry convention in January 1993.
SkyBox International and Marvel added the product to their lines under the names SkyCaps and Hero Caps respectively.
[4][15] Milk caps proved to be major distractions from classes and the source of various playground arguments.
These elements eventually led to the banning of milk caps from various schools across North America.
Milk caps are typically flat circular cardboard discs which are decorated with images on one or both sides.
Traditional (or traditional-style) milk caps are made of rougher cardboard, are printed with limited colors, and often have a staple in them (as they appeared when used as actual POG bottlecaps), while modern commercial pogs were stiffer, thicker and are often printed with colorful glossy imagery.
The other equipment that is used is a slammer: a heavier game piece often made of metal, rubber, or more commonly plastic, which come in various thicknesses and weights.
Metal slammers are not allowed in some games because they are usually heavier than other materials, giving the player with the first turn an unfair advantage, and have a tendency to damage the milk caps.
[9] Menko (めんこ, 面子) is a Japanese card game played by two or more players, dating back to the 17th century.
Each player uses Menko cards made from thick paper or cardboard, printed on one or both sides with images from anime, manga, and other works.