E. Gerber Mylites are made of Archival Polyester (Mylar), an inert material of the highest clarity. Mylites will not discolor, damage, or adhere to items placed inside it. It is a sturdy film that beautifully displays, timelessly protects and gives extra support to fragile documents. Mylites are resistant to moisture, insect attack, fungus, mold, mildew, acid, oils, grease, and solvents. Mylites contain no dangerous plasticizers, slip additives, surface coatings, antioxidants or acid- hydrolysis. Mylar is the strongest plastic available with 1/3 the strength of steel. Use the material specified by the National Archives, the Library of Congress, and the preservation experts around the world.