Keyless entry and starting for your car is convenient and user-friendly, but it does leave you vulnerable to hi-tech thieves. These criminals use relay attack devices to ‘read’ the key from outside your house. With the code copied, they can simply drive off in your vehicle. 

Storing your key in a Faraday bag, lined with layers of metallic material, is the way to foil them and keep your car safe. The key needs to be placed inside the bag from the moment you plip the locks. If large enough, it can also be used for a mobile phone and credit cards to prevent hacking and fraud. So which is the one to keep your keyless car safe? We put eight to the test.

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How we tested them

With the key in a bag alongside the handle, we tried to open the door and then attempted to release the locks by pressing the buttons. Inside the car, we tried to start the engine. 

We used an app to check for phone, WiFi and Bluetooth signal-blocking. Each product’s build quality was also rated (gaps in stitching can allow the signal to escape), plus size and practicality were balanced against cost per gram. Prices were taken from online sources. 


In a test where all the products worked perfectly, points scores were very close. Based on value, build and practicality, we reckon the best overall signal blocker is the Defender, with the key-only Disklabs KS1 and Ecence close behind. 

  1. 1. Defender Signal Blocker 
  2. 2. Disklabs Key Shield Faraday Bag KS1
  3. 3. Ecence RFID Radiation Protection Bag 


Defender Signal Blocker

Price: Around £5
Size (cm): 18.5 x 11.5
Rating: 5.0

In terms of numbers, the Defender is impressive; it’s the second heaviest choice, at 42g, only just the second largest and the cheapest by some margin. The app showed that cell, WiFi and Bluetooth signals were totally zapped with the phone in the wallet.

It’s big enough for one of the new generation of big-battery phones (at 155 x 75mm), and we could also squeeze in a flat Renault key, although a BMW version was a little bit tight. For use only with a key, it’s bulky, but probably worth it for the good build quality, the phone option and that brilliant price tag.

Disklabs Key Shield Faraday Bag KS1

Price: Around £17
Size (cm): 12 x 10
Rating: 4.5

Disklabs is unique in having the ‘Secured by Design’ police accreditation, which inspires confidence. We really liked the quality, with extremely strong stitching on the thick material and the impression you get is that this will withstand many years of use. At 120 sq cm, this pouch will fit all keys easily. It worked very well, even with the flap open and the key inside. And although the price is far from cheap in this company, its quality makes it an investment, especially for those who are going to use it many times a day, all year round. 

Ecence RFID Radiation Protection Bag

Price: Around £7
Size (cm): 12.5 x 8
Rating: 4.5

Available from Amazon, this is identical to the Halfords and B-G offerings. The material is thick and not dissimilar to that of the Disklabs, although we found the join along the lower edge was a bit amateur – it hadn’t actually split, but with regular use it might soon start to. The pouch has clearly been designed solely for key protection, and fitting was a bit tight, especially when pushing the key out from the bottom. All the car’s signals were successfully blocked and it was also competitively priced, which placed it above its two cousins.

B-G RFID Keyless Entry Car Key Fob Signal Blocking Faraday Bag MIS1003

Price: Around £10
Size (cm): 12.5 x 8
Rating: 4.0

B-G offers a choice of two Faraday bags, the second being larger and suitable for phones, and about the same size as the Defender, with a price tag of £12.99. This smaller version matched the Halfords and Ecence note for note, sharing similar positive and negative points. On the back is a simple chrome ring, presumably for hanging in the house, and there’s also a conventional key ring attached to the top. Clipping on the car key meant it was almost impossible to get in the wallet, and other keys (house, office) could be fitted, although it made everything quite clumsy. 

Halfords Anti RFID Theft Wallet

Price: £10
Size (cm): 12.5 x 8
Rating: 4.0

The third of the B-G/Ecence trio, the Halfords lost out on price, but all other aspects were the same. We liked the general feel of the wallet; it seems strong enough to cope with regular use, ignoring that ungainly join. The two-ply copper prevented all signal leakage and the interior compartment would be handy for notes and parking tickets. Unlike the other two, it specifically mentions its use for credit cards; it would take a few alongside a key. 

TVL Anti Scan Wallet

Price: Around £18
Size (cm): 14 x 9.5
Rating: 3.5

TVL’S wallet is similar to the TrackingUK version and also blocked phone signals while the flap was held shut. Another vinyl wallet, it felt better made and should handle constant opening and closing, but might not be so good at being regularly folded into a pocket or handbag. However, it was over
50 per cent heavier (if still far from hefty), at 26g. It stopped all signals, but it was the second priciest choice and topped the list for key-only wallets.

Disklabs Phone Shield Faraday Bag PS1

Price: £24
Size (cm): 11.5 x 19
Rating: 3.0

The larger, phone-sized Disklabs offering mirrored the quality and style of its smaller sibling, as well as the official police accreditation. It’s a bit bigger than the Defender, and could handle both sample phones and blocked all signals to keys and phone, although fitting a bulkier (VW, BMW etc.) key with a phone was tricky. Initially it seemed expensive, but the price per gram was a little below average, although it couldn’t match the top-value Defender.

TrackingUK Faraday Key Signal Blocking Wallet

Price: Around £12
Size (cm): 14.3 x 10
Rating: 3.0

At just 16g, the TrackingUK wallet was the lightest here, making it unobtrusive and easy to fold into
a pocket when not in use. We’d worry about the durability of the vinyl construction and stitching, but it certainly cut all the signals on the keys. It even worked with an iPhone 6, albeit with the flap held tight shut – not a practical application, but a good test. In most cases, it could handle a pair of keys, but it’s hard to ignore that fairly high price.

Now your keys are safe, why not take a look at the best steering wheel locks on the market?


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