Possible for all models. All 4-row models have two semitones in the outermost treble-side row as standard. (Low tones available at extra cost.)
Air key: All models feature a central air button. A long air key (9 cm) can optionally be installed.
Housing: Larger housing possible.
Buttons: Greater number of treble and bass buttons available on request.
Bass buttons: The second bass row has major chords (transition bass series) as standard. On request, minor chords in the second bass row are possible on all models. Transition bass also possible in the first bass series (X-Bass).
Veneers: Custom veneers available for all models.
Inlays: Various patterns and designs are available at extra cost.
Bellows: Custom bellows are available on request.