For years I have been pretending this RFID blocking passport case is protecting me from a phantom menace.
I am not sure from whom, I am not sure from what, and the only proof I am protected is that I have not yet been sucked into a Jason Bourne-style action adventure while traveling overseas. A foil envelope, wrapped in nondescript nylon and naugahide, apparently blocks people from scanning the embedded RFID chip in my US Passport. The manufacturer and various reviews claim it works, I simply needed a passport wallet and it was on the rack at about the same price as non-RFID wallets.
Travelon RFID Blocking Passport Case