Duel Disk

A Duel Disk is a piece of Dueling equipment attached to the left forearm within the Yu-Gi-Oh! franchise. They were first manufactured by KaibaCorp as a portable form of Dueling Arenas used in the early part of the Yu-Gi-Oh! second series anime. They use a portable hologram generator to display Duel Monsters cards and in the case of the Mark 1, the player's hand. Cards that are played are placed on the Duel Disk's blade. Since their introduction in the anime and manga, they have become a fundamental necessity among Duelists.