Kapek (Morbodoni) Chemnitzer in C. In other words, the G and A rows sound concert pitch. I believe that this is a quad. It has six stops for various reed combinations yet is not as big as my Arno Arnold Bb "Slimline". In wonderful shape and tune with a good hard case. $500.
Geuns Student Model C-system Bandoneon. Purchased used from Harry last year. He went through it and tuned it before shipping. Upgraded buttons. Comes with backpack gig bag. These aren't available anymore