Flexible polypropylene Display Book 100 views, A4 With a matt structured flexible polypropylene cover, anti stain and anti scratch, the Opak display book, also called document or book cover, is an economical product for everyday use. Its anti-reflective grained pockets allow you to classify A4 documents and consult them like a notebook. Easy to transport, light and flexible, it is very practical to protect documents and keep them in hand, dry in any situation.