This listing is for a 1980s vintage Gemini MX-1250 studio/live/club audio mixer with 2 stereo busses and 5 band equalizers. The mixer measures 8-1/5" high (5 rack units in a standard 19" rack). I wasn't able to find documentation online although use is pretty self-explanatory.
The video shows a brief demonstration (eBay limits videos to 60 seconds) of a stereo line input, microphone, metering, and equalizer. Backlighting works for all four meters (see pics). Item specifics are available upon request. The last image in the listing shows the PC speakers used for the demonstration (not included). While not the best sounding, they were readily available.
Have questions? Let me know...