Archive for the HP ProBook 450 G4, labelled with the X83 platform code, a pattern typical of Quanta project naming for HP. The contents are not described, but at about 1 MB it most likely holds a boardview or a compact schematic. This material helps locate components, follow power rails and find test points while diagnosing no-power or shorted circuits. Check that the project code printed on your motherboard matches, because related ProBook generations use different Quanta boards.
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 @alischematics. 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.