BCW Chroma Inner Sleeves are an acid free, archival quality product that is designed to protect your valuable cards and help obscure the backside. The BCW Chroma Inner Sleeves are made of two panels of archival-safe polypropylene: one panel is glossy-clear and the other is solid blue These sleeves fit perfect inside a regular card sleeve doubling the protection on your card and making the combination virtually waterproof. The price of a pack of inner sleeves in negligible against the price of replacing expensive cards.