: This specifies that this file is the 9th sequential segment of a larger, split archive.
Multi-volume archives split data evenly. Every single part (except for the very last part in the sequence) must have the exact same file size down to the byte. Right-click part08.rar and check its size properties. Compare it to your corrected part09.rar . MIMK-159-u.part09.rar-
They make it easier to resume interrupted downloads, especially if your internet connection isn't reliable. They also help with file hosting websites that have size limits, and they improve recovery chances if a file is corrupted. The . part09.rar in your file name indicates it's the 9th piece of a puzzle. : This specifies that this file is the