These 2 mil and 4 mil record sleeves are made ofmuseum gradeArchival Polyester
(Mylar), an inert material of the highest clarity. Polyester will not discolor, damage or adhere to items placed inside it. It is a sturdy film that will give extra support to fragile documents. We use DuPont inert Melinex or a suitable equivalent. Polyester is used worldwide in
museums, libraries and archives. Our polyester material is approved by the Library of Congress for archival storage. This material has passed the Photo Activity Test.