New resonance holes
This mechanism will add two resonance keys to the lower part of your instrument.
Low E lever
A thumb key lever next to the thumb rest will allow you to open the resonance keys. When pressed they will raise the pitch of the E or F. Otherwise everything will play the way you are used to. This mechanism is lighter and allows you to choose when to raise the pitch or not.
On-demand, we can make the thumb lever adjustable, so that the hight and angle position can be adjusted.
You can take off the keys and close the holes with bumpers if you don't need it and like to play on a lighter instrument. This allows you to play in tune when it is critical.
Improved low E sound
Besides that the low E will play in tune, you also will experience a much-improved sound for the E. It fits much nicer into the scale and has the same sound color as the low F
Thump operated low E/F correction mechanic on an A clarinet Improved low E sound