An International Reply Coupon (IRC) is intended to be purchased by a mail sender to be included in the mail to be sent. The recipient can then exchange the IRC at a post office for stamps covering the charge for a foreign standard/priority letter back to the sender. 

The IRC itself is a printed piece of paper which will be stamped by the post office with a day cancellation upon purchase. IRCs are authorised by the Universal Postal Union (UPU) and are either issued by UPU itself or by a country being member of the UPU. Their validity is within countries being members of the UPU. The design of the IRCs have been labelled 

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IRCs are in existence since 1907. Over time they have been changed in design multiple times, each of which is labelled with a city name followed by "model", ie "Lausanne model". The city name was based on the location of the respective UPU Congress where the decision on the next IRC design was being made.

 

Finland joined the UPU in 1918 and began with the sale of its own IRCs in the same year. The first known year of Finnish IRCs being used in Aland is 1957. The start of more frequent sale and use of IRCs in Aland dates back to the 1980s with the Lausanne model.