During the hyperinflation in the Weimar Republic it became increasingly difficult for the Imperial Printing Office in Berlin to produce new postage stamps to keep up with the frequent rate changes.
Consequently, out of necessity, locally produced fee paid stamps (aka local issues) were officially approved and were therefore valid for postage.
However, some dealers also seized the opportunity and produced their own labels.
The brothers Sekula collaborated with these dealers in creating philatelic collectibles by serving them as recipients of the travelled covers.
The cover below was mailed registered on September 18, 1923, from Brunswick, Germany, and reached New York City on October 3, 1923.
It shows correct franking of M200,000.- for international letter up to 20 g plus M75,000.- for registration.
The fee paid labels were privately produced by stamp dealer Walter Behrens, Brunswick, Germany, and went through the postal system for about two weeks without objection.
See also the same cover to Béla Szekula