The dos-à-dos book is an old one that was bound in the late 16th century. It contains six books, all neatly hidden inside a single binding. They are all devotional texts printed in Germany during the 1550s and 1570s. The book is currently being held at the National Library of Sweden.
Each book is held with a metal clasp
Unlocking one opens one of the six books
The book not only has incredible craftsmanship, but is extremely rare