1 May 1967 - 30 June 1971
US foreign surface letter rate 13 c
Swedish foreign surface letter rate 70 öre
US handstamp shows amount to pay in US cents (normally double deficiency) and US surface letter rate.
In Sweden the indicated fraction multiplied by 70 and rounded up to nearest 5 öre was normally paid by affixing stamps on the item.
Double rate air mail letter with 20 cent. Correct rate 40 cent. Shortpaid 20 cent. US due handstamp indicates double deficiency 2x20=40 cent and surface letter rate 13 cent. Amount due in Sweden, 40/13 multiplied by Swedish foreign letter rate 70 öre = 215.38 rounded down to 215 öre paid by affixing postage stamps. Normally the amount should have been rounded up to 220 öre but the handling clerk probably thought it was so close to 215 so he only charged this amount.