High quality card sleeves from KMC, card sleeve manufacturer in Japan, the sleeves to protect your valuable card collections. Plastic card sleeves are devices used to protect trading cards from damage, especially collectible card game cards from wear and tear and to store them. Thanks to the trading card industry, there developed a wide variety of protective devices, including the bulky "top-loader", a rigid plastic case with one open end (essentially a box for a single card) and the less-expensive simple "card sleeve," a card-sized envelope of Clear plastic, with one end open. The term may also refer to pocket pages Designed to store trading cards in binders or card albums. Once collectible card games became popular, new technology was needed.