Tuning pin
tuning device of the drone
Inserted in the stopped lower end of a Regulator to enable easy tuning by manipulating its traditionally spherical knob.
Pushing the pin in, sharpens the notes, pulling it out, flattens them.
Breathnach, Breandán: The Irish pipes. In: The bagpipes in Europe, 1 (1976), p.3, 4.
Garvin, Wilbert: The Irish bagpipes: their construction and maintenance [Belfast 1978, Blackstaff Press]. Foreword by Breandán Breathnach. Kells, 1988 (2), p.20.