RAR archive of about 295 KB for the ASUS P8Z68-V motherboard, the base model of that series; no revision or file type is given in the name. Open it to confirm what it holds, most likely boardview data given the size. Such a file is used to find components, trace rails like VCore and DRAM voltage, and locate the BIOS chip and its supply when repairing a dead board. Be careful not to confuse it with the PRO, LE or LX variants, and compare the PCB revision with anything stated inside.
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 @boardview. 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.