Apple boardview for the MacBook Pro 16-inch, model A2141, covering logic board 820-01700. The .brd file maps every component, net and test point on the board, so a technician can follow power rails, find where a short sits and probe signals without a full schematic beside it. Open it in a boardview viewer such as OpenBoardView, FlexBV or a similar tool. Apple prints the 820 number on the PCB, and it should match 820-01700 before you rely on any part location or net name taken from this file.
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 @boardviews. Enginerys does not host this file.
How to open a .brd file
The most common boardview extension. Several unrelated formats share it, which is why one viewer opens a .brd and another refuses it.