crystal clear, gloss polyester film reveals your bks' vibrant graphics and protects them from oil, dirt, grease, spills and rain. Unique film allows bks to slide on and off the shelves without grabbing the bks beside them for easier browsing and re-shelving. Adjusts to any bk size with easy to use perforated liner; white paper backing offers added protection and allows the bk jacket to simply slip into the cover. UV-resistant film protects bk jacket covers from fading. Acid-Free and 100% archival safe.