Package for the ECS B75H2-AM-DNI motherboard, revision A, about 1011 KB in RAR form. The B75 in the model points to the Intel B75 chipset generation. Documentation of this sort is used to follow power rails, check the CPU VRM and standby circuits and locate components during no-power diagnosis. The name does not say what the archive contains, so unpack it first. Confirm the PCB silkscreen shows B75H2-AM-DNI and Rev A, since the related B75H2-AD is a different board.
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 @IT_SERVICE_WORLD. 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.