Artist Classic Portfolio 23"x31": Transport, store and protect your artwork in these classic portfolios. Perfect for students, theyÆre made of a durable, water-resistant nylon. They feature bound seams for added durability, a removable and adjustable shoulder strap with a no-slip shoulder pad, an ergonomic carrying handle and a full-length easy glide zipper. Sized two inches larger than stated dimensions in each direction.