Holbein girdle book, c. Leather girdle book (right). Girdle books were popular during the to and were typically religious or devotional works on parchment or paper, bound in leather or an ornate enameled metal case.
Personal prayer-book/diptych belonging to Philip the Good, Duke of Burgundy. The combination of diptych and devotional book is unique in the history of art. Built around 1430 - Century, Austrian National Library, Vienna