Questions? Please call us 650-226-8119. The resealable adhesive strip of the transparent bag is underneath the opening of the bag instead of on the flap. Our acid-free whitecore matboards are a 4-ply papermat that offers the aesthetics and design benefits of a white wadding. Each sheet mat board has a rich coloured face, a white core and a white background. Can be used for matte photos, art and needle point Also great for crafts, backboards, signs, childrens projects, and school projects