Hornbostel - Sachs
Sets of open flutes with internal duct
The air itself is the vibrator in the primary sense. The standing waves are significantly confined within each flute, where a narrow duct directs the air stream against the sharp edge of a lateral orifice. The opposite end is open. Two or more flutes are combined to form a set. The instrument has no fingerholes. Open flue stops of the organ.
Sets of open flutes with internal duct without fingerholes
Sets of open flutes with internal duct without fingerholes combined with set of partly-stopped flutes with internal duct
Sets of open flutes with internal duct without fingerholes combined with set of partly-stopped flutes with internal duct with keyboard
Mechanically driven sets of open flutes with internal duct without fingerholes