ZIP archive, about 1.5 MB, named IH61W-MHS, which appears to be a desktop motherboard model; the H61 portion suggests the Intel H61 chipset but the name does not confirm the maker. Contents are not described, so it may hold a BIOS image, schematic or other service files. If a BIOS dump is inside, read and save the original SPI chip with a programmer before writing, and make sure the image size equals the flash capacity. Match the board model on the PCB before use.
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 @cyberlanelectonik. 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