A 95.0 KB PDF named after the 2SK1908, listed in the schematic section of the index. Since 2SK is the Japanese registration prefix for N-channel FETs, treat it as the component datasheet for that transistor. Its main use at the bench is confirming which leg is gate, drain and source, plus voltage and current limits, before measuring in circuit or picking an equivalent. No brand or package is given in the name, so check the printed code on the part against the document.
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.