The overprint issues used throughout the German colonies were replaced in 1900/1901 with a standardized design, featuring Kaiser Wilhelm II’s yacht, the Hohenzollern II.
The 1901 Yacht Issues can be distinguished from subsequent Yacht Issues by the units of currency and the watermarks:
1901: Pesa/Rupien values, no watermark
1905: Heller values, no watermark
1905/1920: Heller/Rupien values, lozenge watermark
Proofs of several values (MiNr. 11, 19-21) exist. Among these is this imperf proof of MiNr. 11.