RAR archive related to the main board of the LB-LINK BL-CPE450H, an outdoor CPE wireless unit. The name says only that it covers the chassis main board and gives no hint of whether it holds a schematic, photos or a firmware image, so the 5.43 MB contents must be checked after extraction. Material like this helps a technician compare component placement, trace power and RF sections, or restore a bricked unit. Make sure the hardware revision on your PCB matches before relying on anything 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 @biositechyangiyer. 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.