.7z is a high-compression archive format developed by 7-Zip.
The .001 extension indicates this is part 1 of a multi-part split set (e.g., KIA.7z.001 , KIA.7z.002 , KIA.7z.003 ). KIA.7z.001
You cannot extract the contents from .001 alone. You must have all parts of the archive (001, 002, etc.) in the same folder before beginning extraction. KIA.7z.001
Using 7-Zip, open or right-click the KIA.7z.001 file. KIA.7z.001
It is recommended to use the 7-Zip utility for Windows, or apps like Unzip One or RAR Lab for other platforms. How to Extract