Archive in RAR format named Z97-C, which corresponds to a desktop motherboard model using the Z97 chipset. The name gives no file type, maker or revision, so its contents must be checked after extraction. The 289 KB size points to a boardview or a schematic fragment rather than a firmware dump. A technician typically uses such material to trace power rails, find shorted components and locate test points. Verify that the board revision printed near the slots matches the files inside before relying on them.
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 @boardview. 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.