1,Acid free mat board 2,Various color and multi openings. 3,Professional design and quality. 4,Economic Price. 1. A lot of colors ... core, white core, black core of mat board3. Lignin free and acid free4. Thickness: 0.5mm--3.0mm5. Bevel cut, reverse ... *7", 8*10", 11*14", 27*31" and other sizes are available8. A variety of design, prints and colors9. Professional quality and economic price.