If you're dealing with a file named M2.part6.rar , you are looking at one piece of a . How to Extract Multi-Part RAR Files

Multi-part files (like .part1.rar , .part2.rar , ..., .part6.rar ) are created to split a single large file into smaller chunks for easier sharing or storage .

Depending on what you are working with, the content of that archive might refer to: Gunsmith Part 6 - RELEASE 1.0 Guide | Escape From Tarkov