McCollum Polystyrene Sample Boards are made from a flexible lightweight plastic .020mm, are flexible like heavy paper stock, waterproof and dimentionally stable. They make the perfect sample boards. Each board is a generous 18 X 24 inches. Polystyrene Boards are a superior alternative to foam core or poster board. Their special matte/matte finish grips to nearly all coatings products including latex paint, oil paint, various faux finishing products, pencils, pens and nearly all artist mediums. They can be easily cut to any size.