Archive for the Apple iPhone 6S in ZIP form, 4.06 MB in size. Its contents are not described by the name, but iPhone packages like this commonly include a schematic and a boardview for the logic board. Technicians rely on them to trace power supply lines from the battery connector and PMIC, check the charging and display circuits and locate components that may be shorted. Make sure the board is a 6S and not a 6S Plus, since the two use different layouts despite sharing many circuits.
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 .zip file
Compressed archive that every operating system opens without extra software.