Wiktionary
stamp hinge
n. A small gummed strip of folded glassine paper, used to mount stamps on an album page.
Wikipedia
Stamp hinge
In philately, stamp hinges, or mounts, are small, folded, transparent, rectangular pieces of paper coated with a mild gum. They are used by stamp collectors to affix postage stamps onto the pages of a stamp album.
Usage examples of "stamp hinge".
Later, I learned of the stamp hinge, but I never liked them much as they never kept the stamps in place in the album.
Stuck to the inside back cover with a yellowing stamp hinge was an old, faded, slightly grubby paper Lifeboat flag, without its pin.