the idea came from Schatten controls, the little thumb wheel potentiometers controllable through the sound whole, so there is no need to drill into the guitar.
while standard guitars may be satisfied with the two Schatten wheels, we need more to control our features.
so Heinz “Rüebli” Fässler came with the idea to organize the thumb wheels in the other direction and we felt that they are even easier to control! just slide the index or middle finger in and out of the soundhole… you can find one end of the pot and then get used to the amount you need to move the finger to get to the value you want!