ZIP archive of 1.53 MB labelled H61MLV2, which points to an Intel H61 chipset micro-ATX board, though the manufacturer is not stated and the contents are not described. It likely contains a BIOS image used to reflash the SPI chip with a programmer when the board fails to post. Identify the board by its silkscreen and revision before use, inspect the extracted files, back up the original flash and verify that the image size matches the chip, because an image of the wrong size will not fit.
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 @schematicslaptop. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.