Harmonicas with the edges removed, with an egg-shaped design. The case and the instrument are made so that their sizes match perfectly and the instrument does not go flying if the cover is removed forcefully. This is also intended to prevent damage.
Looking at the interior of the harmonica, it is apparent that the reed for the lowest note to the far-left is at a distance from all the other reeds. The instrument has been designed carefully, with the chamber where the air flows formed into a long U-shape so that the lowest note can be produced easily.