Specifically, the Court accepted the defendant's argument, raised for the first time on appeal, that the district court erroneously applied an enhancement for the "use" of body armor under USSG 3B1.5. The commentary explained that use of body armor required either active employment to protect the person from gunfire, or use as a means of bartering. The defendant, however, did no more than sell body armor for money, which was different than bartering, as bartering meant trading goods without the use of money. Finding the language of the commentary clear, the Court rejected the government's reliance on legislative history and purpose. And having found that the district court committed an error that was plain, there was not dispute that the remaining plain-error prongs were satisfied.