A file is the first segment of a multi-part compressed archive created with 7-Zip . This specific extension indicates that a large file or folder has been "split" into smaller pieces—likely to make it easier to share via email, upload to cloud storage, or fit onto a USB drive. 🧩 The Anatomy of a Split Archive
When you see a file ending in .001 , it is part of a sequence. For the extraction to work, you generally need (e.g., PA01.7z.001 , PA01.7z.002 , PA01.7z.003 ) stored in the same folder. How to extract part files 001 using 7zip on windows (2026) PA01.7z.001