15 Pfg black overprint with overprint error III "center bar of the 'B' broken" with left margin of sheet along with 2, 8 (with rotary printing upper margin) and 25 Pfg on correctly franked registered letter from "BERLIN-DAHLEM 17.3.49" to Zurich / Switzerland, faultless condition, nice choice copy letter, expertized Schlegel BPP, the overprint error on cover by Michel unpriced