From Pathfinder Lost Omens Pathfinder Society Guide, which isn't enabled.

Ganjay Book (1 bulk book)

ITEM 1

Price 10 gp

Usage held in 1 hand

Bulk L

This item is a formula book, religious text, or spellbook that has been creased-possibly by Princess Ganjay herself-to fold up into an impossibly small shape. When folded up, the book can't be read or used, but its Bulk is reduced by 1 (a book that is 1 Bulk becomes light Bulk, and a book that is light Bulk becomes negligible in weight).

Activate 1 minute (Interact)

Effect You fold or unfold the Ganjay book, manipulating the cunning creases.

Pathfinder Lost Omens Pathfinder Society GuideOGL