I can image that astronauts on ISS are working with books and notebooks. There are procedures for some issue or details of experiment. Working on some experiment where you have a book in one hand can be little bit hard. Better to work with free hands. Idea is to put a book on upper arm and have an access to notes and in the same time have a free hands.

Upper arm handler can be also used in the kitchen. Put there tortilla and be sure that won't fly away. 

Project has one base element and two addons. note_handler is for tortilla and notebook. book_handler is for thick book.