Our Archival Mat and Presentation Kit includes 4-Ply Bright White 100% Cotton Museum Board mat with a bevel-cut window 1/8"" Acid-Free Foam Board backing Crystal Clear bag with self-adhesive closure Clear Mounting corners appropriate for the print size Tyvek Tape for hinging window mat to Acid-Free Foam Board backing Application This complete kit will let you professionally present, exhibit and preserve your artwork, photographs and documents with Archival Methods' museum-quality materials. Window openings are centered for either vertical or horizontal use..