Bruges - Rules of Play says:

Deck Builder's Playset PRO-Binder designed for collecting playsets of your favorite trading card. Each row holds a 4-card playset. Embossed middle black web material, gives cards a classic framed look. Side loading pocket design to prevent cards from easily falling out. Elastic strap holds the binder shut when not in use. All materials made from archival-safe, acid-free non-PVC material. Sized to fit 480 standard sized cards in Ultra Pro Deck Protector sleeves.