Sometimes a large file is split into smaller pieces for easier transfer over the Internet or multiple CDs/DVDs. This command lets you combine file.001, file.002, file.003, etc. back into a single file file, provided that all the pieces are in the same folder.
This command is only for use with files created by other software that are named in the above manner. DropDMG’s segments feature creates files such as file.dmg, file.002.dmgpart, file.003.dmgpart, etc. A segmented disk image can be accessed by double-clicking the .dmg file; it is not necessary to first join the part files. If you do need to combine a segmented disk image and its parts into a single .dmg file, use the Convert Image/Archive… feature.
As a shortcut for Join Files…, you can drag the .001 file onto the DropDMG window or DropDMG’s Dock icon.