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