5 Mark imperial yacht, war time printing, perforation 26 : 17, original sheet of 20 each values, in perfect condition mint never hinged - the sheet margins except for a partly pulled out in of the left upper corner complete extant, the only the BPP expert known sheet this variety, photo expertize Brekenfeld BPP (2021) : \"genuine and immaculate\", Michel for single stamp stamps 7.600.- - rare opportunity!