Compressed ZIP archive of 3.28 MB named X750J, a designation that resembles ASUS notebook naming, although no brand is given and the contents are not described. It could contain schematics, boardview files or a firmware image for that model, so unpack it and identify each file before relying on it. Compare the board code and revision printed on the motherboard with the documents, and when a BIOS dump is included, read and save the original flash contents with a programmer first.
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 @notebookschematic. Enginerys does not host this file.
How to open a .zip file
Compressed archive that every operating system opens without extra software.