As technology makes our lives easier and manufacturers find smarter ways to integrate the latest innovations into cars, new risks arise that criminals want to take advantage of. Years ago, when a thief wanted to steal your car with the key, they went to extensive measures, including fishing through your letterbox in the hope that you left your car keys by the door. Now it’s a high-tech game of cat and mouse as the thieves have turned to stealthy solutions, including electronic boxes to transmit signals from smart keys that allow owners to enter their cars without pressing a button. The answer to this new risk is a Faraday bag.
If your car has a smart key that allows you to enter and start the engine without handling it, thieves may be able to target the frequency unless it is blocked. Once they detect a signal, they can trick the car into opening and driving away without damaging the vehicle or triggering the alarm. This method is gaining popularity among thieves of cars that are stolen to order, or among criminals who want to use the vehicle for other crimes and therefore want to avoid obvious damage that makes the car stand out.
A Faraday bag takes this worry away. Coated with a layer of metal, it essentially insulates your key and its frequency, so it won’t be sent or copied. A Faraday bag also works with smartphones and credit cards.
A Faraday bag will beat the criminals at their own game, but which one is the best? We tested eight to get the answer.
How the Faraday Bags Were Tested
In our first test, we tried our smart key’s proximity sensor by trying to open the door of our test vehicle with the car keys in a Faraday bag kept next to the driver’s door. Then we pressed the button on the key while it remained in the Faraday bag to see if it caused any reaction from the vehicle. Finally we got behind the wheel and tried to start the car with the key still in Faraday’s bag.
We also reviewed the bags’ build quality, cost, and usability. An app was used to check the phone, Bluetooth, and Wi-Fi signal-blocking capabilities.
The results were very close as all the products worked as the manufacturers said. With this in mind, we focused on the quality, usability and value for money offered by each of the products. The best signal blocker was the defender, a Faraday bag big enough for other items. Both the Disklabs KS1 and the Ecence were not far behind.
Defender Signal Blocker
Price: About £5
Size (cm): 18.5 x 11.5″
Our winner successfully blocked all signals and had an excellent build quality. Surprisingly, it is also the cheapest to buy. It’s the second-largest bag of the tested ones, which can easily handle larger phones, but it can be a bit over the top if you only have a small set of keys. We were happy to accept the size, given the benefits the Defender gives you for the price.
Disklabs Key Shield Faraday Bag KS1
Price: About £28
Size (cm): 12 x 10
The Disklabs bag immediately inspired confidence, as it was the only one here to receive the ‘Secured by Design’ accreditation from the police. Build quality here was one of the best and the signal-blocking effectiveness worked even with the valve still open. It would fit nicely with most keys. It’s an expensive choice, but it feels like a good investment.
Ecence RFID Radiation Protection Bag
Price: About £9
Size (cm): 12.5 x 8
Designed for key use only, the Ecence bag is exactly the same as the Halfords and BG, apart from being cheaper, which is why we’ve given it a higher rating. It did the signal well, the material itself thick and comforting. The only complaint we had was the lack of stitching quality, especially on the bottom of the bag and whether it had the potential to wear with use.
BG RFID Keyless Entry Car Key Fob Signal Blocking Faraday Bag MIS1003
Price: About £3
Size (cm): 12.5 x 8
A nice feature of the BG is that you can choose two sizes; a smaller one for keys only or a larger one for items like phones. Construction and results were nearly identical to the Ecence bag, just for a little more money. The BG had a chrome ring on the back, perhaps for hanging the bag from your key holder indoors. There was also a key ring on the top.
Halfords Anti-RFID Theft Wallet
Size (cm): 12.5 x 8
The Halfords bag lost at the price of its cousin de Ecence. However, as with the Ecence and BG, the build and signal blocking were up to standard, save for perhaps the stitching in the bottom of the bag. Unlike its affiliates, the Halfords bag specifically states that it can be used with credit cards. You could easily fit a few in there too.
TVL Anti Scan Wallet
Price: About £24
Size (cm): 14 x 9.5
TVL is the second most expensive here, but as with the Disklabs KS1 and PS1 bag, you could tell the quality would mean it would last even with everyday use. The liner worked well for blocking the key signal and also worked with phones when the flip was closed. The vinyl coating adds to the sturdy feel, but doesn’t bode well for folding it into a pocket.
Disklabs Phone Shield Faraday Bag PS1
Price: About £31
Size (cm): 11.5 x 19
The most expensive but also the largest, bigger than the Defender. The PS1 also has the same police identification as its smaller brother, the KS1. It could fit inside phones and keys, with only a little effort when accommodating larger sets of keys. Despite the price, the size makes it worth the extra expense, although it would be a bit too cumbersome to easily keep in a pocket or purse.
TrackingUK Faraday Key Signal Blocking Wallet
Price: About £12
Size (cm): 14.3×10
For subtlety, the TrackingUK bag was the best. It was by far the lightest of the set and easy to fold and store. Blocking phone signals was a bit more hit and miss, but it worked perfectly on the keys. However, the price for the quality of material and stitching seemed a little steep, especially as it didn’t seem as durable as some of the other options here.
Looking for other ways to protect your car from keyless go theft? Read our guide to the best steering wheel locks to stop thieves.