BCW Silver Comic Mylar Bags 4 Mil - (Case of 10 Packs) Archival Collecting Supplies Made of Archival Polyester (Mylar) 25 Bags per pack Fits standard Silver Comic Books Size 7 1/2 x 10 1/2 4 mil material thickness - 1 1/2 inch flap for closure Strength is 10 times that of polyethylene Protects for 100's of years