This is an internal DVD-R/W drive from a Dell Optiplex 7020 but it fits many Dell models -- go by the Dell part number of the drive: 0V3171.

This came from a working system that was retired due to a replacement of all computers in the firm that owned it, not because there was anything wrong with it.  I usually test things like this drive before taking apart a computer, but this time I forgot.  So the drive is untested, but is guaranteed to work.  I think there is a very strong likelihood that is is fine.  I've priced it lower than I would have otherwise.