Zagreb rouletted, blue-black overprint, plate I / I, letter front-homeland to Troisdorf with letter cancel the fieldpost number 58391 C of the on the island Postmark with Upper Circle Segment stationed rod and 2. Company XI. Fortress Infantry Battalion 999, to the adaptation the fieldpost numbers to the island post time has the unit the fieldpost number 68097 (Fasch. Flak department Coo and rod and 1.-4. Company XI. Fortress Infantry Battalion 999 - Island part) see sender, a genuine flown out commercial letter, whose stamp the cancellation escaped is, detailed photo expertize Mogler BPP, wherein the traces no reference found