Black Premiere Playset PRO-Binder - Rules of Play says:

The Ultra PRO Black Premiere Playset PRO-Binder is designed for collecting and storing playsets of your favorite trading card. It features a NEW double-fold compact design. Each row holds 4-card playsets. Each page is backed with embossed material to give cards a classic framed look. Side loading pocket design to prevent cards from easily falling out. Powerful magnets strategically positioned hold the binder shut when not in use. All materials made from archival-safe, acid-free non-PVC material. Sized to fit 480 single-sleeved standard sized cards in Ultra PRO Deck Protector sleeves.