A compact 50 KB PDF named after the JEDEC-registered part 2N720A, indexed under schematics but almost certainly a component datasheet rather than a board drawing. The trailing A marks a variant of the base 2N720 type. Open it in any PDF reader to check pinout, package outline, absolute maximum ratings and electrical characteristics before fitting a substitute. Always compare the marking on the original part and the case style with the drawing in the document, since 2N numbers are made by several vendors.
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.