16 pfennigs worker series, vertical strip of three, upper and middle stamp with post horn ribbon type overprint normal and inverted (Michel number 42 INKc), lower stamp with inverted overprint (Michel number 42 IDK), mint never hinged, faultless, expertized Schlegel BPP and Dr. Dub, photo expertize Schlegel BPP (1983) "genuine, defects are not present", Michel 330.-