MSI MS-7158 archive in RAR format, 1.04 MB in size. The name carries only the brand and board number, so its contents, possibly a BIOS image or a small document set, must be confirmed after extraction. MSI desktop boards follow the MS-7xxx numbering, printed on the PCB with a revision. Ensure your board matches before use, and when flashing firmware with a programmer, back up the existing chip and check that the image size equals the chip capacity.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.
7-ZipWinRARThe Unarchiver (macOS)