1,Acid free mat board 2,Various color and multi openings. 3,Professional design and quality. 4,Economic Price. 1. A lot of colors ... --3.0mm5. Bevel cut, reverse bevel cut, V-groove 6. Multi layers and multi openings7. 4*6", 5*7", 8*10", 11*14 ... ", 27*31" and other sizes are available8. A variety of design, prints and ...