50 cent airmail (first issue 1928), two values being a correctly franked multiple franking on air mail letter with red confirmation box cancel of 2 lines "with airmail transported Karlsruhe (Baden) 1" from Saarbrücken to Karlsruhe, photo expertize Ney VP (2016) : "the depicted, flawless stamps as well the postmark on the correctly franked cover are genuine. "