6 Pes. 25 C. on 5 Mark "Reichspost", block of four with following types (from left above to at the bottom on the right) : 19 I / IV plus 19 I / III plus 19 I / I and 19 I (IV, overprint type I, mint never hinged, very fine, extremely rare unit, expertized Georg Buehler and photo expertize Ronald F. Steuer BPP "extremely rare unit. in perfect mint never hinged condition. ", Michel 5.550.- plus plus