The Studio B2 is a wonderfully compact convertor accordion.
Only 6.5kg in weight but with a 37 note range on both the Right hand and freebass keyboards this allows you to cover a huge amount of repertoire.
The right hand has 61 buttons giving you a range of 37 notes from G to G and is a 2 voice model. This is available as octave tuned or as a 2 voice unison.
The left hand has 78 bass stradella keyboard that converts to a 37 note freebass with a note range C to C.