The format was intended to help Dungeon Masters (DM) keep handy only the monster statistics needed for a particular game session, as well as to greatly expand the information about each monster, as each was given at least one full page. It would also mean they would only need to purchase core volumes and appendix volumes for the campaigns they wanted, rather than getting a mix of monsters in books. However, the binder format ultimately proved impractical for two main reasons. First, looseleaf pages were not as durable as the hardcover format. As it was a frequently used game aid this was a serious concern. Second, TSR routinely printed different monsters on each side of a sheet, making it impossible to keep monsters in strict alphabetical order.