Heckel (100)

high-A-key+C#-key connection on the wing-joint

What: high-A-key on the wing-joint automatically opens C#-key

Advantage:
high-A and high-Bb are played with the high-A-key only (rather than the high-A and C# keys combined) facilitating slurs to higher notes requiring the high-C-key.

Note:
A (below middle-c) cannot by vented ("flicked") with the A-key.