RAR archive labelled for the Apple iPhone X, about 6 MB in size. The name does not list its contents, so expect a schematic, boardview or similar service material for that phone, but open it to confirm. Phone repair archives of this kind are typically used to trace power lines, locate components and test points around the logic board, and diagnose shorts. Boardview files are viewed in programs such as OpenBoardView or FlexBV, schematics in any PDF reader. Check that the board revision matches your unit before relying on it.
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 @cyberlanelectonik. 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.