Original, untested, Electrohome G19 arcade game CGA (standard resolution) monitor chassis. Definitely not a common chassis, we don't recall seeing one in the past 20 years. Apparently it was the last monitor Electrohome made and they didn't make many of them. Consider this one needing repair or sold for parts: it is missing its neck board and has been sitting for many years. It looks like a mouse got to the rubber anode cup as it has been chewed up and will need to be replaced.
It does look to be otherwise complete, but it is untested and sold as-is.
Please note: working with monitors involves high voltages and can be dangerous. If you are not familar with monitors we do not recommend installing an item like this.