PA Specialty Framing Mats let you turn your photos and artwork into dramatic and exciting home decor pieces that can be hung on your walls, displayed on an easel, or even decoratively framed. Double layer mat with both layers having beveled edges. Double 16"x 20" 20-Openings White Core Black/Black- Measurement is exterior size. 20-Openings are a collection of rectangles, ovals, a square, and an octagon, sizes vary from 1.5"x 2.5" to 5.5"x 3.5". Black upper mat with Black inner mat, both with White core bevel. Acid free but for Non-Conservation Framing.