Cembalo Universale 'false inner-outer' with 19 keys per octave
From the seventeenth century onwards, more and more 'false inner-outer' models were built in Italy, which only feigned the separate instrument standing in the outer case. This one, called Clavicymbalum Universale by Praetorius, has 19 keys per octave and thus offers a variety of usable keys in meantone, if one has learned to handle the keyboard.