Herzberg modifications

Whisper-key (L-t) is square in shape and curved so that when sliding to it from the c#-key, the L-t is less likely to slip off of the whisper-key. Available in conjunction with rollers on c#/whisper-key.

F-key, Ab-key (R-4f) curved to prevent sliding off.

Bb-key, F#-key (R-t) curved to prevent sliding off.

Wood toneholes (those without silver tubes) in the wing-joint and in the small bore of the butt-joint are sealed along their length by [heat treatment?].