To open RAR files, you can use WinRAR, which is the software made by the company that invented RAR technology. To open .001 files, you need another program, such as HJSplit, 7-Zip or File Joiner.

How to Combine RAR Files in WinRAR. The RAR format optionally splits large files into several compressed parts. This multi-part format makes distributing large business files to or from customers ...

Occasionally, you'll need to open several compressed files from one ZIP folder. While Windows does a fine job extracting, there are better tools to unzip.

The Unarchiver app is free to use and can open a range of popular archive file formats, including rar, zip, 7-zip, Tar, and Gzip, in addition to older and more obscure ones. To extract a rar file ...