Duplicate copy of the 2SK2043 datasheet, describing an N-channel MOSFET rated 600 V and 2 A according to the name; the trailing (1) only marks a second saved instance of the same 105 KB PDF. The sheet covers absolute maximum ratings, switching characteristics and package dimensions. Technicians refer to it when a power supply blows its primary switch, checking for a drain-source short with a multimeter and sourcing a substitute whose voltage, current and gate specifications match.
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.