The EX Starter Box (also known as Duel Monsters EX) was released on December 16, 1999. Although it is usually considered as part of Series 1 in the Yu-Gi-Oh! OCG instead of being grouped with the later Structure Decks, the EX Starter Box effectively contained the first starter decks in the OCG, and later formed the basis for the Yugi and Kaiba TCG Starter Decks, with all 85 cards in the EX Starter Box being released in the English Yu-Gi-Oh! TCG.
Like other cards printed early on in the game, these cards have no printed set numbers, and lack the distinctive holographic "Eye of Anubis" in the lower right-hand corner of each card.
(Despite the similarity in names, it is worth noting that the EX Starter Box and the later EX-R Starter Box—also known as Duel Monsters EX-R, released November 23, 2000—are, in fact, two different sets. Although they share 85 cards, it is easy to distinguish those from each set, since there are differences in specific card rarities, and EX-R cards sport both printed set numbers and the holographic "Eye of Anubis".)