Gamegenic Prime Ring-Binder Black - Rules of Play says:

The Prime Ring-Binder is equipped with 3 durable D-rings to carry standard-sized 18- or 9-pocket pages. It is covered with Nexofyber surface which provides an elegant look and comfortable feel while being water-repellent. The inside of the Prime Ring‑Binder is covered with soft microfiber lining. A label slot at the back can either hold the flippable label or a standard-sized gaming card. With this the binder can be individually marked or labeled. Reinforced front- and back-covers add a thick layer of protection to provide a safe place for any card collection.