I'm guessing that this fastens under a stage and reflects light through the sample on the stage, but honestly, I'm not sure what it is.
It has the same finish as a some Carl Zeiss items we have had, but there are no names or numbers on the body.
The mirror can be angled as desired and a set screw holds the position. The aluminium section (O.D. 33mm) is where it fastens , but the black body is hinged, so you can move it.