This accordion is an instrument used by Viljo Vesterinen. It has had several owners over the decades, and in 2021 the instrument was overhauled and restored to its original appearance. Among other things, the treble buttons were remade to be square shaped. Vesterinen played the so-called B-system, but this instrument has the so-called Finnish system. The treble key conversion work was probably done at the Oy Harmonikka factory in Kouvola when the accordion was reselled.