Anonymous wrote:https://about.usps.com/postal-bulletin/2012/pb22352/html/updt_005.htm

Global Forever stamps can be used to mail a postcard or 1-ounce letter-size mailpiece anywhere in the world, regardless of when the stamp is purchased and regardless of how prices may change in the future. Helping to ease the transition during price changes, the Global Forever stamp is sold at the price of a single-piece First-Class Mail International 1-ounce machinable letter, and has a postage value equivalent to the price of a single-piece First-Class Mail International 1-ounce machinable letter in effect at the time of use (mailing).

For this price change, the Global Forever may also be used to mail a 2-ounce letter-size mailpiece to Canada, because the 1-ounce and 2-ounce letter-size mailpieces to Canada are the same. To help distinguish between the domestic and international forever stamps, the international version will always be round and will always bear the words “Global Forever.” The initial offering of the Global Forever stamp features a picture of a globe. Finally, as with the domestic Forever stamp, mailers have the flexibility to use these stamps as postage for any type of single-piece international or domestic mailpiece.