2 1 / 2 on 2 1 / 2 Groschen large shield in a mixed franking with 1 Groschen large shield on an internal mail service, cancelled with a circular postmark "DORTMUND ST. P. E. 2 27. 9. 74" and the rare first violet adhesive label "Dortmund Stadtpostexp. II. / Auslagen" to Cologne with a rear arrival postmark of 28. 9