Small RAR archive of 754 KB named only SX, which says little about the device it belongs to. It may contain firmware, a plugin or configuration data for a receiver, but the name alone does not confirm the content. Open and inspect the files, check any readme or internal model strings, and compare image sizes with the target flash before use. Never program unidentified data onto a working device without first reading and storing the original memory contents.
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 @tvsoftwareworld. 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)