50 - 9 1/2" x 20" Brodart Archival Fold-On Book Jacket Covers -- Center-loading, Clear, Mylar, Adjustable These high quality book jacket covers are Center-Loading for Dust Jackets up to 9 1/2" tall. The covers are 1.5 mil in thickness. Super Clear polyester mylar Overall dimension of these Book Covers are: 9 1/2" Tall x 20" Wide. Closed edges are permanently bonded. Paper backing for added protection.