Pokemon Mewtwo PRO Binder 9-Pocket - Rules of Play says:

The Ultra PRO 9-pocket PRO-Binder stores and protects your collectible gaming cards while showcasing detailed, full-color art from the highly popular Pokémon Trading Card Game. Embossed low-friction black backing material gives cards a classic framed look. Side-loading pocket prevent cards from easily falling out in transit. Elastic strap holds the binder securely shut when not in use. All materials made from archival-safe, acid-free non-PVC materials. Holds 360 Cards in Ultra PRO Deck Protector sleeves.