10 Pfg to 1 Mark postage stamps issue with overprint \"Plesbiscite 20 mars 1921. \", complete set in vertical gutter pairs, impeccable mint never hinged, because the stamps not really as all sets or even in multiples to be on sale were allowed it concerns an with this set about a major rarity, the hardly ever offered becomes, expertized Landre and photo expertize Gunnar Gruber BPP: \"very rare. This gutter set is a large Upper Silesia rarity. The stamps are genuine and in perfect quality. \"