The series of “Piano” model Hohners came in three stages. This photo shows all three of the Piano 26 models plus a Piano 20. The second one down, to which Lowboy just referred, was the first, introduced in or by 1961. This continued in production through the 1970s, and they vary a bit in color, light gray to dark, and even a very dark wine color as shown in some ads). The third one down is from the second series, which appeared late 1960s to early 70s. It’s shown in the photos with which Lowboy started this thread. At the bottom is its stablemate Piano 20. At the top is the late 1970s to 2011 third series Piano 26. They all have the “darker” sound, though each model has its own distinct tones. The Hohner Cassottos are from the third series. Each series has its Piano 27.