Storing phones in odd places has become a favorite practice of those afraid of spies infiltrating their devices. National Security Agency leaker Edward Snowden famously asked visitors in Hong Kong to stash their phones in a refrigerator. And it's not an unfounded fear: it is theoretically possible for even a phone that is powered off to be actively listening.

Tools for combating surveillance have become a new frontier for design experimentation. The latest is from the Austrian design firm Coop Himmelb(l)au and looks very much like a large Snuggie made from a comforter that also happens to block radio signals.

The futuristic Gandalf cloak, dubbed the CHBL Jammer Coat, operates as a kind of Faraday cage and uses "metallized fabrics" to block radio waves and tracking devices that might, for instance, lift credit card info from RFID chips. The coat is part of an exhibition of "work clothes" for the Milan Triennale that will run from June through August.

The coat is preceded by many other obfuscation clothes: at Toronto Fashion Week, designer Kunihiko Morinaga showed a line of metallic shielded clothing that blocked radio signals. Designer Adam Harvey also created a set of garments that are meant to block thermal imaging and X-rays; they also had Faraday-cage pockets. And for the thriftier, more conservative concerned citizen, there is a range of lovely signal-blocking pouches, some of dubious functionality.