FIRST DAY USAGE OF THE 6 KR 1851 Folded cover from Ettlingen to Frankfurt franked by 6Kr black on blue-green tied by “42” numeral, clear ETTLINGEN 1 MAI 51 first day cancel alongside, reverse bears TPO pmk from the same day, the 6Kr is touched as often the case with this issue and the cover is somewhat toned, attractive and very rare first day cover Expertise: cert. Stegmüller (BPP) Estimate: € 4’000 – € 6’000 (Image)