The high conductive side of the notch window is fixed and is selected by the notch switch.
When the notch width switch is on narrow (to the left) the high conductive side of the notch window is fixed to be just above square tabs.
When the notch width switch is on wide (to the right) the high conductive side of the notch window is fixed to just above zinc.
The notch width dial controls the notch window setting for the lower conductive side and is adjustable.
So with the notch switch on the narrow side (to the left) and the notch width dial turned all the way clockwise, the notch window is just the size of most older squaretabs. As you adjust the notch width dial counter clockwise, you will begin to lengthen the notch window to include more types of square tabs, then round tabs, then nickels and finally down into the high, then middle foil range.
If you click the notch switch over to wide (to the right) you raised the high end of the notch window to include zinc cents.
Maybe that helps.
HH
Mike