Vintage Kern Aarau Model 48081 Full-Circle Manual Polarimeter with Wooden Case.
I am unable to test this unit and do not even know if it is complete, so I am offering it "as is", with no returns.
The plastic-like material around the eyepiece is cracked, and there is some green corrosion or adhesive underneath it.
Other than that, it appears to be in good overall condition for its age.
Comes as shown in my pictures. Please see my pictures for more details.