Datasheet in PDF form for the 2SK2058, a part number in the Japanese JIS 2SK series, which designates N-channel field-effect transistors. Although it is filed under schematics, a document of 99.2 KB named after a semiconductor part is almost certainly a component datasheet. Use it to confirm pinout, package outline and maximum voltage and current ratings before replacing a failed FET, and compare the markings on the actual device with the sheet, since the name gives no manufacturer or variant.
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.