The suggested format is BRF with 10 MB volumes. This display will not open a file larger than ten megabytes. The dictionary files can be opened and navigated in the book reader or Victor reader application. Please note that, as of version 2.3 of the software, you can't unzip the dictionary files on the display itself, and the file manager will crash if you do. This is not a problem with the files, it is a problem with the software on the display. To get around this, please unzip the dictionary files on your computer and copy them to the display.