The file is the second part of a multi-volume 7z archive . Because it is a split file, you cannot open it individually; you must have all numbered parts (starting with .001 ) in the same folder to reconstruct the original data.

Have you ever downloaded a file only to find it has a strange extension like ? If you try to double-click it, your computer likely won't know what to do.

How to extract files from a split 7zip archive? - Ask Ubuntu

Large files are often split into smaller "volumes" to make them easier to upload or share. usually ends in .7z.001 Part 2: ends in .7z.002 (this is the file you have!) Subsequent parts: .7z.003 , .7z.004 , and so on. 2. The Golden Rule: Collect All Parts