Lineco Cotton Rag Museum Mounting Boards are 4-ply matboards made from 100% cotton fibers, with solid color throughout. Every board is acid-free, lignin-free, and buffered with 3% calcium carbonate. These affordable, high-quality boards dont compromise on quality. - Lineco Cotton Rag Museum Mounting Boards - Pkg of 25, Black, 11" x 14"Museum Mounting Boards, BLK 25PKG 11X14IN -