Aarne Koski made his first accordions around year 1915 at Inkeroinen, Finland. As far as it is known, his second accordion was finnished in early 1920’s. The instrument was a six row accordion. Both of these instruments were flat bed accordions with wooden body and metal corners. However, the accordion in the picture is or might the first Aarne Koski’s accordion with steps in the diskant side. The mechanism is on its own level: the melody side mechanism is resembling sligtly bass mechanism by having pushing metal arms. The bass mechanism can easily be taken off. The bass side is made by a watchmaker Eero Forsman. The whole mechanism can be lifted up after turning three locks aside. Kielipenkit ovat pohjasta myös omanlaisensa ja ne ovat tervaleppää. The reed blocks are unique and they are made from alder. Johan Homan’s accordion, which was studied at Aarne Koski’s shop, most likely has not been a model for this accordion. Therefore this accordion might be manufactured before year 1922.
Diskant metal grill is having similar leaf patterns than what can be found from a same era accordion made by Wiitalähde (In Canada). Bass mehcanism resembles a lot pf modern days German accordions which are having a cassette bass mehcanism.