The application is designed for those that poses no means of opening the CBR and CBZ files. The reason for this is that CBR and CBZ are themselves a different kind of archives but they are mainly used in delivering comic book content.
The ZIP and RAR conversion function seems a bit odd but for it to work your ZIP and RAR archives must only contain images. Obviously it converts CBR and CBZ files to PDF format, but it can also do the same with ZIP and RAR files. CBR and CBZ to PDF is a straightforward application that tells you what it does from its name alone.
