ASUS K53SD BIOS in .bin format, marked in the name as New MCS. The suffix is not explained and most likely labels a newer copy rather than a hardware variant. The 4 MB size corresponds to a 32 Mbit SPI chip. Repair shops use such an image to recover a bricked laptop by programming the chip directly. Take a backup read of the existing chip, check that it is also 4 MB, and compare the motherboard revision before relying on this dump.
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 @biosfilebins. Enginerys does not host this file.
How to open a .bin file
A raw, byte-for-byte image of a flash chip: the main BIOS / UEFI, the embedded-controller (EC) firmware, or both.
Back up your own chip before writing any dump, and match the full board number and revision. Flashing guide →