1, 50 Karbowanez with overprint "GK-Ssarny" in type X, position 6, properly franked single franking on cover from "DOMBROVICA -7 11 41" to Sarny with arrival postmark "Sarni -a 10 11 41", cover vertical folding right, stamp spot of glue - through affix the ungummed issued stamps, photo expertize Gerhard Krischke BPP "the letter is properly franked franked also used. Such commercially used letters with stamps in type X are extremely rare. "