Koncovka

Koncovka is a Slovak duct-blownovertone fipple flute without finger holes, traditionally played by shepherds. The koncovka flute is played by closing and opening the bottom hole of the flute. By increasing the air speed, two different harmonic series of notes can be played with the end either open or closed. Traditional koncovka melodies use the partial Lydian scale available on this instrument.

...
Wikipedia