Game card sleeves are outer sets used to protect and decorate game cards. Here are some common game card sleeve characteristics:
 

Size fit: Game card sleeves are often designed to fit specific game card sizes to ensure the set fits the cards perfectly. Common sizes include standard card holders, mini card holders, large card holders, etc.

Material: The material of game card sleeves is usually soft, transparent plastic, such as polyvinyl chloride (PVC) or polypropylene (PP). These materials offer durability, transparency and protective properties that protect cards from damage and contamination.

Transparency: Game card sleeves are usually transparent or translucent so that players can clearly see the content and design of the cards. Transparency can also showcase a card's value and rarity.