Applying a clear Mylar cover to the dust jacket of a book ensures the durability of that jacket. If you receive processing on your books and select to have Mylar applied, the processing will be placed on the dust jacket and the Mylar will be applied over the top of it. If you do not select to have Mylar applied, the processing will be placed on the book itself. The cost of Mylar is $.50/book with a $.20/book handling fee. (The $.20 handling fee is waived if you purchase a processing package. Canadian version here.) Mylar is only available attached and is only applied to books with dust jackets. You may change this selection at any time by contacting Customer Service.