Beginning in 1905, Germany began phasing in the use of watermarked paper on its new issues.
This practice eventually led to the introduction of new Yacht issues which were similar to the 1900 issues, but featured a lozenge-shaped watermark.
The 3 Pf and 5 M values were never postally used due to the fall of the German Togo. The stamps were only sold at philatelic sales windows in Berlin.
MiNr. 23 I A is a “peace printing” issued in Jan 1915, and therefore shows different qualities from the remaining “war printing” (1919) issues of this set. It is lighter in color overall, with better quality paper and printing.