Sheets of plastic sleeves for storing and displaying baseball cards, or any other type of trading cards, can be purchased online or in person from various hobby and specialty stores. Online mass retailers, such as Amazon, also sell supplies for trading card collectors.
Many baseball card collectors store their cards in specially designed plastic sheets. The most common sheets feature nine slots for storing cards and come with pre-punched holes that allow the sheets to be placed in a standard three-ring binder. Basic sheets feature a slot on the top that allows the cards to slide in and out easily. More expensive sheets feature locking mechanisms that afford a higher level of security and protection.