His passport lay against his chest, beneath his shirt, in a Faraday pouch protecting the information on its resident RFID tag. RFID snooping was an obsession of Sleight’s. Radio-frequency identification tags. They were in lots of things, evidently, and definitely in every recent U.S. passport. Sleight himself was quite fond of RFID snooping, which Milgrim supposed was one reason he worried about it. You could sit in a hotel lobby and remotely collect information from the passports of American businessmen. The Faraday pouch, which blocked all radio signals, made this impossible.