This is another in the family of membrane reed wind instruments, along with this, this, and this. You can visit those pages to get a sense of what membrane reeds are and how they work. For a greater level of detail, see this article. The instrument on this page differs from those in that it has a tabletop keyboard system for opening and closing tone holes. This makes it possible to have tone holes that are larger and farther apart than fingers alone could cover, allowing a wider and lower range. Unlike the elaborate keying systems of orchestral winds like clarinets and saxophones, the tabletop keyboard system is made in a way that’s manageable in a home workshop. (But designing the keyboard system is not quite as simple as it might seem; you can find a fuller discussion of that in the above-linked article.) I’ve also used a similar keyboard system in a lower-pitched version of the Breath Flute.