Tiny folded squares of thin glassine paper that are gummed on one side. Just like a door hinge, they allow one to mount a stamp and then lift the stamp lightly (without removing it from the page) to examine its back. See illustration. One can buy packages of 1,000 hinges for about $1.00. We would recommend using hinges on only the least valuable of stamps and/or on stamps that have already been hinged some time in the past. This is especially important when one is mounting mint, never hinged stamps on which the full gum is still on the stamp.