Component documentation for the 2SC2120 in a 198 KB PDF, categorised as a schematic. Its JIS-format number places it among NPN bipolar transistors, so expect a datasheet with pin configuration, package dimensions and tables of voltage, current and gain. Technicians reach for it when checking a transistor out of circuit, verifying base-emitter and base-collector junctions, or selecting a replacement with matching ratings. Note any rank letter on the part body, since gain grades are usually listed separately in such sheets.
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.