North Vietnam, Butterflies, November 18th, 1965, Michel Nr. 405-410; Six stamps in the nominals of 12 xu (four stamps), 20 xu and 30 xu were issued perforated 11.0 and im-perforated. The im-perforated stamps are quite rare, more so than other stamps that were issued on that basis.
Here is the entire set im-perforated in mint blocks of four:
Here is a registered letter sent to Klewitz with the entire mint perforated set. The overall franking amounts to 1.12 Dong which is slightly above the required tariff of a standard register letter to West Germany of 1.10 Dong.
Very rare registered express letter sent to Klewitz with the entire im-perforated set. The overall franking of 4.98 Dong is most likely too high as a standard registered express mail letter to West Germany only cost 1.60 Dong. Im-perforated stamps on postally used cover are very rare.
Air mail letter sent from Hanoi to a State owned company in East Germany from November of 1965. The letter carries a mixed franking (including the 12xu Butterfly stamp) for an overall postage of 38xu. Since the standard letter rate to East germany in 1965 was only 12xu (up to 20g) this letter must have been heavier than the standard.
Registration Nr. 101200