14 June 1921 at Karlovy Vary 2

The cover is canceled on 14 June 1921 at Karlovy Vary 2 / Karlsbad 2 with a Czech Post cancel.  It was addressed to Bad Harzburg, Germany.  Based on the cancels on the back, I can determine that the cover traveled by train east from Karlovy Vary to Děčin, Czechoslovakia.  It then traveled north to Dresden, Germany where it was opened for currency control as shown by the tape and cancels on the back.  From Dresden the envelope traveled by train via Leipzig and Halle to Bad Harzburg, where it arrived on 10 July 1921.  Bad Harzburg is located in central Germany, just east of Goslar in the German state of Lower Saxony.  The total postage on the cover is 29.05 Crowns.  As I do not have access to a Czechoslovak Post rate chart for 1921, I do not know what services are covered by the postage.
There are two additional markings on the front of the envelope.  One is a red “4 in a circle.  The other is a violet “41” in a triangle.  I do not know the meaning of either.  On the back the three strips of sealing tape applied at Dresden Altstadt, are tied to the envelope with three strikes from the “Postüberwachungsstelle, Dresden.” Post Monitoring Office, Dresden).
Any information on postage rates or the two markings on the front would be appreciated. Email Tom Cossaboom at KLFCK1 at aol.com