3 Karbowanez with overprint "GK. Ssarny", position 4, type I, properly franked single franking on registered letter with cancellation "CSELCSEWALEWO -5 12 41" (last day) with arrival postmark "SARNI 2 -a -6 12.41", cover heavily damaged, stamp faultless, photo expertize Gerhard Krischke BPP "the registered letter is properly franked franked also used. Commercially used letters of this kind are extremely rare. ", Michel 4.500.-