The Metropolitan Museum of Art in New York started handing out those now-iconic metal tags with its "da Vinci M" logo to visitors in 1971. Today, admission-control litho tabs, as they're officially known, are standard in museums around the world, and a handful of companies, including Adco Litho Line of Broadview, Illinois, and New York's Kraus & Sons (which makes the Met's tabs), stamp out millions of the rust-resistant tinplate-steel pieces each year. If you buy in bulk, they cost about 9 cents each.
Lately, many museums have been switching to plastic tags, which cost much less than their metal forebears and are more user-friendly. Ketchum Manufacturing of Brockville, Ontario, stopped producing metal tags after receiving numerous complaints. "The more we investigated it, we found that women didn't want to put that metal onto a blouse, and children were cutting themselves on the sharp edges," says owner Claude Lalonde. "In fact, we were nearly sued when a child cut his finger." Ketchum now produces 10 million plastic tabs each year.