Chalk this one up to the quirks of the English language. The other day, we had a post on the recall of a small number of 2014 Nissan Leaf EVs that were missing weld spots. The official bulletin from the National Highway Traffic Safety Administration said that "any vehicle missing welds will be replaced, free of charge." We read that as saying that the welds would be replaced, but in fact it's the cars themselves that will be swapped out.
Bulging in the exhaust system like a rabbit deep in the belly of a boa, the catalytic converter cleans engine fumes before they are released into the air. To the inexperienced, the oversized metal cylinder looks rather uninteresting. To a thief, it is a pod of precious metal worth nearly $200 on the black market.