It is the largest museum of its kind in Scandinavia featuring mechanically produced music from instruments dating from the 1850s to the present. They offer a 70-minute guided tour in which visitors see and hear most of the museum's 290 instruments. The instruments are displayed in eight large rooms, each decorated in a style corresponding to the machines they hold.
If you are going to be in Finland, I would say that Mekaanisen Musiikin Museo would be worth a visit.
[ Thanks Kristiina! ]