Datasheet-style PDF for the 2SK1117, with the name noting NTE2379 as its equivalent, meaning the NTE replacement line lists that part as a cross-reference. The 2SK prefix marks an N-channel FET under the Japanese JIS numbering. At 26.6 KB it is likely a short sheet with key ratings and pinout. Useful when sourcing a substitute for a damaged power transistor; verify drain-source voltage, current, package and pin order of the NTE part against the original before soldering it in.
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.