The Poké Ball is a spherical device used by Pokémon Trainers to catch wild Pokémon or store their own Pokémon. It was designed to be lightweight, practical, and effective. Poké Balls can store Pokémon, regardless of weight or size, in a very small space by converting the Pokémon's matter into energy. There are many types of Poké Balls, and ordinary ones have an upper red half and a lower white half that are separated by a black line circling around the Poké Ball. There is a button in the center of the Poké Ball, and although its purpose is not shown in the main Pokémon series of games, the Pokémon anime shows that the button activates the Poké Ball, causing it to slightly increase in size.