Archive of 2.03 MB named only by the code 3CESLRH11, apparently the next revision after RH10 in the same series. No manufacturer, model or content type is stated, so the contents are unknown until you unpack it. Look inside for a firmware image or documentation and compare its identifiers with labels on the hardware. If you program a chip with it, take a full backup of the original contents first. Also verify that the file size matches the chip capacity.
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.
7-ZipWinRARThe Unarchiver (macOS)