We manufacture polyester sleeves here at Bags Unlimited. Our trade name for this material is Archival Armor. Polyester is the one storage material for paper products that is used by the Library of Congress. The reason for this is that the life of polyester is indefinite. That means that the material will not break down for hundreds of years. Not only is this material as clear as glass, but it is semi-rigid, has composition properties that do not react in anyway with a stored item, it does not discolor nor does it adhere to items placed in it. From the perspective of an archive organization, this is a perfect storage material. Fortunately we are able to provide you with this exact same material in five sizes for different eras of comics and also offer several different thicknesses and styles to choose from.
We made a video showing you the different style of polyester sleeves that we make. Watching this video should help you decide which sleeve is best for your storage needs.