Archive tied to Apple logic board 820-2936, revision A, as used in the 13 inch MacBook Pro A1278. The name gives only the board number with an lb prefix for logic board, so open it to see whether it holds a boardview, schematic or firmware. Material for this board helps trace power rails, find test points and diagnose shorts. Boardview files open in OpenBoardView or FlexBV. Check that the 820 number and revision on your board match before relying on it.
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 @schematicslaptop. 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.
7-ZipWinRARThe Unarchiver (macOS)