PDF covering the BF458 and BF459 transistors, a compact 49.2 KB file listed as a schematic but most likely a shared datasheet. These are high-voltage small-signal NPN types typically used in video output stages of older CRT televisions and monitors. The sheet should give collector voltage ratings, gain, power dissipation and the package pinout. Use it to identify leads before in-circuit testing and to choose a replacement, noting that the two numbers differ in voltage rating, so confirm which one is fitted on the board.
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.