The Hohner HM-26, Piano 26, though introduced around 1980, was still on the market until 2011. It was identified as a soprano, its counterpart Piano 27 as an alto. These models did not change much over the years. It’s debatable whether the range of these instruments justifies identification as soprano and alto, but if the HM-26 is what you have, it’s genuine. It is shown below. The HM-26 (or 27) has a distinctive sound that some of us like, though it’s not appreciated by everybody. Lowboy Bootay is the biggest advocate of these models here and has developed incredible playing techniques that make use of the fact that most of the sound emits through the holes in the bottom. These were the last models manufactured in Germany before Hohner dispatched its melodica manufacturing to China, which has resulted in more generic melodica design in the current models. Check out, by searching, some of Lowboy’s sound samples.