Latest Beyerdynamic T1 2nd generation (serial number 31,829).
A T1 second generation highlight is the detachable cable. The cable is provided with a gold-plated mini jack connector (3.5 mm) and gold-plated screw-on 1/4" adapter.
Note from Head-Fi: Beyerdynamic made a sliding mechanism improvement on units with serial numbers above 30,000. The difference is noticeable using the mechanism and is also visible in the depth and shape of the holes on the iron frame.