International registered air mail letter to North America (category IIIa) < 5 gr.
Postage rate 40 öre, registered mail fee 40 öre and air mail fee 0 öre
Since 1 Dec. 1947 no air mail fee to the U.S., provided 5 gr. written in upper left corner
Registered mail label type 5:1
01/06/52 - 31/05/57