1 Mark large internal service with double red "Danzig" overprint. Second overprint shifted approx. 0,3 mm upwards and leftwards, basic stamp colour and gum structure minimally altered by solvent exposure, very good perforations, unused with original gum, signed Z. Mikulski, Star, Hochkeppler, Ruberg and H.S., expert certificate Z. Mikulski AIEP and certificate Volker Erdwien BPP; the alterations are still tolerable given the rarity, only one sheet (20 examples) known, Mi. 5.000.-