After performing a successful file system analysis, FolderSizes enables the Command Prompt feature (accessed by clicking the OS Tools button in the application ribbon bar).
Selecting this tool causes FolderSizes to launch a command prompt window (e.g. a "DOS window") within the active folder path.
This feature is also exposed through numerous right-click (e.g. context) menus throughout the FolderSizes user interface. You can even right-click a file and select this option, in which case the command prompt window is launched within the file's parent folder path.