Clothespin wiki:
othespin (also C47, clothes peg, or just peg) is a fastener used to hang up, and dry clothes, usually on a clothes line. Pegs often come in many different designs.Today, many pegs are manufactured very cheaply by creating two interlocking plastic or wooden prongs, which in between is often wedged a small spring. By a lever action, when the two prongs are pinched at the top of the peg, the prongs open up, and when released, the spring draws the two prongs shut, creating the action necessary for gripping.
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