Small RAR archive named M57 DVT MLB, 174 KB, with no brand stated. MLB normally stands for main logic board and DVT for design validation test, an early pre-production build stage. The contents type is not indicated, so it could be a boardview, schematic or related documentation. Extract and check before relying on it. Since DVT-stage files may differ from retail boards, compare component layout and board markings with the actual unit carefully when tracing rails or locating parts.
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 .rar file
Compressed archive — the usual wrapper for a schematic + boardview pair or a BIOS + EC set.