MSI MS-6596 package, a 6.35 MB zip archive. Only the brand and board code are given in the name, with no revision or content type. The larger size suggests more than a bare firmware image, possibly a full schematic set or several BIOS versions, but that must be confirmed by opening it. MSI uses MS- codes for its own motherboards, printed on the PCB. Before relying on the files, match the board number and revision, and back up the existing BIOS chip before any reflash.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @IT_SERVICE_WORLD. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.
Built-in OS tools7-Zip