PDF of 140 KB for the 2SK2739 with an unexplained 1-5 suffix, which may indicate an edition or page count rather than a different part. Under the Japanese JIS system the 2SK prefix identifies an N-channel field-effect transistor, so the document is effectively its datasheet despite the schematic label. It serves for checking the pinout, drain-source voltage, current capability and on-resistance when testing or substituting the device. A plain-named version of the same part is also listed for comparison.
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.