Heinrich Band lived at Krefeld(Rheinland/Westfalen)West Germany.

He was a music teacher, musician and publisher.
Band had his instruments made to the order, most probably at Saxony (perhaps by Zimmermann or Uhlig).
Contrary to the Konzertina he later expanded the lay-out by adding more rows of keys instead of lengthening the already existing three rows, like Zimmermann and Uhlig were doing.
Band`s intention was to simplify the change from a small instrument lay-out to the larger instruments as players improved their musical skills.

This instrument had already a very complete range containing all the tones of the chromatic scale. The "mushroom" buttons at the top are stops. A small lever behind the air valve, operates a mechanical <tremolo>device which gives the playing air a pulsating effect by means of a complicated bellow system inside. It is surprising to see in how short time, the bandonion has developed  in such short time.

Band improved the sales of musical notes by adding numbers besides, and later over the notes corresponding with the keys at the instruments.
 This made the selflearning process of playing easier (most people didn`t have any knowledge of musical notes neither could they pay for a music teacher).
Also bandonion&concertina tutors were published. This way of learning bandonion was, and still is very popular in Germany today.

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Source: http://www.bandoneon-maker.com/bandonions.htm