1943, 2 zloty \"structure barbican in Cracow\", proof in steal blue (pure blue) of the original engraving plate with four engraving lines on gummed paper in the size 112 x 74 mm, line perforation 14 1 / 2, handwritten notation of the steel printers with colour number (?), perforation opened and in the margin the printing plate strong through embossed, rare, very decorative, expertized Ludin BPP with certificate