You receive a good book with quality pages. The spectator has free choice among the three objects- key, phone, pen. And whatever they chose, you can predict the correct output. But the book cannot be inspected by the spectator. Also you might know how this works. The spectator cannot closely look at the book because they might see little line along the edge of the book where it separates it as 3 parts. That part can be seen easily if they look close. That is the only draw back here
