Are these a scam?

Personal Faraday shields can be effective for blocking RF signals to protect items like car keys and credit cards, but are largely unnecessary for cell phones which are better managed with airplane mode.

• Most personal Faraday shields, including DIY options, effectively block RF signals for key fobs and credit cards.

• For cell phones, airplane mode is a more practical and effective solution than a Faraday cage.

• RFID blocking in wallets works even without a full enclosure due to low signal range and power.

Personal Faraday shields, from commercial products to DIY solutions, were tested for their ability to block RF signals to protect against car theft or card skimming. While many products and simple household items effectively block these signals, using such a shield for a cell phone is generally impractical and less effective than simply enabling airplane mode. The tests revealed that even an incomplete enclosure like the Ridge Wallet can block RFID due to the low power and range of RFID chips.

Testing Methodology for RF Shields

• 00:00:26 To accurately assess personal Faraday shields, a controlled environment was essential, achieved using an EMC chamber that reduced RF to near zero. An RF meter and various shields, including commercial products and a DIY version, were used. The core test involved placing a cell phone as a transmitter inside the shield and measuring the EMF strength with a receiver, establishing a baseline without a phone and then within the chamber.

Effectiveness of Commercial Faraday Bags

• 00:03:48 The Hadui bag, when properly folded, proved highly effective, bringing the RF measurements down to levels functionally identical to an empty chamber. Initial tests showed significant RF emissions from a phone searching for a network, ranging from 650 millivolts to 2.5 volts per meter. The Samfoke box and other bags also performed similarly, confirming their ability to block signals when fully enclosed.

Practicality and Misconceptions of Cell Phone Shielding

• 00:06:12 While Faraday shields are useful for protecting wallets and key fobs from skimming or car theft, their application for cell phones is often misrepresented. Putting a phone in airplane mode offers the same security benefits with none of the downsides, as a phone inside a Faraday cage will continuously search for a connection, draining its battery. Most companies market these products for cell phone use without understanding how phones operate.

DIY and Other Shielding Solutions

• 00:08:18 Many common household items can serve as effective RF shields. Aluminum foil, a DIY reusable bag with foil tape, a metal cookie tin, and certain types of ESD-safe bags all successfully blocked signals during testing. The Ridge Wallet also effectively blocked RFID, demonstrating that a complete enclosure is not always necessary due to the low power and range of RFID chips.