Listed under schematics, this 133 KB PDF named 2SC5108FT appears to be the datasheet for an FT-suffixed variant of the 2SC5108 transistor. By JIS convention 2SC marks an NPN bipolar device; the suffix distinguishes a version of the base number, so package and specifications should be confirmed from the sheet rather than assumed identical to the plain part. Use the package drawing to verify lead order and match collector voltage, current and dissipation ratings when sourcing a replacement.
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 @cyberlanelectonik. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.