Compressed package for the Gigabyte GA-H81M-D3H, an Intel H81 micro-ATX motherboard, 742 KB. The name gives no hint of the contents, so unpack it and confirm whether it holds a BIOS dump or a schematic. Firmware images like this are used to recover boards that do not POST, by rewriting the SPI chip with an external programmer. Check the board revision silkscreened on the PCB and the flash capacity. Save the original dump first to keep the MAC and serial data.
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.
Built-in OS tools7-Zip