From the cover sheet:
This deluxe pleather dice tray with the Elder Sign will keep your dice safe when you play Call of Cthulhu.
The dice tray packs flat with your Call of Cthulhu rulebook but is ready for action with a simple press of each corner stud.
From publisher blurb:
Approximate assembled dimensions: 9.5″ (24cm) Length × 6.75″ (17cm) Width × 1.5″ (3.8cm) Depth