: Use a trusted tool like 7-Zip or WinRAR to open it. These tools allow you to "Open Archive" to see the contents before actually extracting them to your PC.
Since the file name is obscure, follow these steps to manage it safely: M13SHP.rar
Do you have a where you found this file, or can you describe the contents if you've already opened it? : Use a trusted tool like 7-Zip or WinRAR to open it
: It could be a private backup file from a specific user or local server. How to Safely Handle This File M13SHP.rar
: Occasionally, hardware components use alphanumeric codes like this for compressed update packages.