Since i am in the mood for Prexie cover, i will talk about one example that i like. This cover above is franked with Scott# 830, 831 and 833. IT is send via Airmail To China With $2 Prexy 30c and 50c all tied with New York NY Oct 31 1946 CDS on #10 envelope.

It is addressed to Shanghai China, paying 4 times of 70c Airmail rate. From my research Oct 31st, 1946 was the last day for this rate, this cover would have cost only $1 the next day. A very uncommon cover and postal history.