The Itoya RB-11-17 Art Profolio Multi-Ring Refillable Binder (Portrait, 11" x 17") has a sleek, contemporary exterior with durable steel binder rings. It has a rigid polypropylene cover, but is still lightweight for easy transport. It has a unique, center mounted, multi-fold spine that allows the Art Profolio Multi-Ring Refillable Binder to lay perfectly flat for presentations. It uses the PolyGlass refill sheets, that feature crystal clear clarity. It includes one pack plus bonus sheet. It is archival safe and acid-free.