Sweden. PS-försändelse Facit PS1 cover, Stamp for foreign postal office mail, with 6-pointed stars, on PS-cover sent from STOCKHOLM C 9.9.1879 via PKXP Nr 2 10.9.1879 to Heligoland, which entered UPU only a few months earlier, on 1.7.1879. Exceptional scarce destination, no mail recorded to the British Administration of Heligoland according to Ferdén. Highly interesting exhibition item.