With two flutes playing at once it's as if a small band has struck up.
The chanter has six finger-holes and is in a diatonic major, like the penny whistle (tin whistle, Irish whistle). Here it is paired with a second flute acting as the drone (bourdon). When over-blowing forcefully on the drone, overtones are produced which match the chanter.
The two slits of the windways permit to play the flutes together or separate.
A side-hole in the drone gives the capacity to play in a minor key.
Drone-flutes with one or two tunable drones
The flutes are connected by an adapter made of juniper. They can be blown separate by different blowing holes in the adapter or be taken out of the adapter and played a a single flute.
The drones have several tuning holes, closed by cork.
C - whistle, 6 fingerholes - major
drone 1: C, D, E, F
opt. drone 2: E, F
D - whistle 6 fingerholes - major
drone 1: D, E, F#, G
opt. drone 2: F#, G