Prussia 3 Sgr. postal stationery cover with double circle. Hamburg 9. 12. being an international letter to Warsaw with arrival postmark, on face with handwritten notation "Kastenbf" (box letter) and "fr. Border" as well taxe "10" (Kopecks) the from receiver taken in were, with the Ganzsachenporto from 3 Sgr. was only the union rate up to the border franked, rare partly franked letter to Poland, cover at the bottom a little toned and small corner fault, attest van der Linden BPP