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If your car unlocks when you walk up to it with the key in your pocket, thieves may be able to steal it without ever touching your key. The trick is called a relay attack, and the cheapest defense is a Faraday bag or box for your key fob.
We read the Associated Press report on keyless car theft, which quotes the security engineers at Thatcham Research, and compared the most popular key fob pouches and boxes. For phones, laptops and other gear, see our main guide to the best Faraday bags.
We research, we don’t lab-test. Everything below comes from the sources listed at the end and the product listings, checked in October 2026.
In this guide:
- The Short Answer
- How Relay Theft Works
- Is Your Car at Risk?
- Faraday Pouch or Faraday Box?
- How to Test a Key Fob Pouch at Your Car
- Free Fixes: Fob Sleep Mode and Car Settings
- Our Picks: The Best Faraday Bags and Boxes for Key Fobs
- Our Verdict
- Frequently Asked Questions
The Short Answer
Yes, a Faraday bag for your key fob is worth it if your car has keyless entry. Use a pouch when you’re out and a box by the door at home, keep every fob in one (spares too), and test it at your car. Our pick is the Mission Darkness Faraday Key Fob Bag (2-pack), the only one here whose maker names the test standards it meets. For a budget pouch, the TICONN Faraday Bag for Car Key Fob (2-pack) is the most-reviewed. For home, the Samfolk Faraday Box with Faraday Bags holds the whole family’s keys.
How Relay Theft Works
Many newer cars use a wireless fob and push-button start. According to the Associated Press, the fob keeps giving off a short-range signal even when you’re not using it, and the car unlocks when it senses the fob nearby.
Thieves exploit that. One person holds a device near your front door or near you in a parking lot to pick up the faint signal. A second person stands by the car with a device that repeats it, so the car thinks the key is right there. The car unlocks and starts. The AP report describes the whole thing taking seconds.
A Faraday bag or box stops this by blocking the signal. It’s lined with conductive metal mesh, so the fob’s signal can’t get out while it’s sealed inside.
Is Your Car at Risk?
Relay theft targets cars with keyless (passive) entry: the doors unlock as you walk up, or the car starts with a button while the fob stays in your pocket. Check for these signs:
- Your car has a push-button start and you never take the key out of your pocket or bag.
- The doors unlock when you touch the handle, without pressing the fob.
- You park on a driveway or the street close to where you leave your keys at night.
If you have to press a button on the fob to unlock and turn a key to start, relay attacks are not the main risk for your car. A pouch still won’t hurt, but it’s less urgent.
Worried someone is following your car rather than stealing it? That’s a different problem. See our guide to finding a tracker on your car.
Faraday Pouch or Faraday Box?
Both do the same job, so pick the one that fits how you live. Many households use both.
| Faraday pouch | Faraday box | |
|---|---|---|
| Best for | Carrying your key when you’re out | Home, by the door or bedside |
| Number of keys | Usually one fob | Several fobs, often a whole family’s |
| Easy to forget? | You have to seal it every time | Easier: drop keys in and close the lid |
| Weak point | Flap not fully closed, worn seams | Lid not fully closed |
Whichever you choose, the seal is everything. A pouch with the flap half open or a box with the lid resting on a keyring won’t block anything.
How to Test a Key Fob Pouch at Your Car
This is the test the experts quoted by the AP recommend, and it takes 30 seconds:
- Put the fob in the pouch or box and close it fully.
- Walk up to your car and try the door handle.
- If the doors stay locked, the signal is blocked. If they unlock, the bag is leaking.
- For a box, leave it near the car with the lid closed and try the handle and the start button.
Repeat the test every few months. Linings crack and seams wear, which is why many Faraday bags stop working over time.
Free Fixes: Fob Sleep Mode and Car Settings
Before you buy anything, check whether your car can switch off the keyless signal. The AP report lists a few options:
- Toyota: on many smart keys, hold the lock button and press unlock twice. The light blinks four times, and the key stops sending its signal until you next press a button. Toyota’s manuals call this a battery-saving function.
- Ford, Honda and Audi: on some models you can switch off keyless entry in the touchscreen menus.
- Motion-sensing fobs: some newer fobs go to sleep when they haven’t moved for a while. Ask your dealer if yours does.
- Bought a used car? Ask a dealer to reprogram the keys, in case a previous owner kept a fob.
The catch: these settings vary by model and year, and you have to remember to use them. The AP report also says to ignore internet advice about putting your fob in the freezer or microwave, which doesn’t work like a Faraday bag and can damage the key. A steering wheel lock is another cheap layer that police forces suggest, because it makes your car a slower target.
Our Picks: The Best Faraday Bags and Boxes for Key Fobs
We chose these from the most-reviewed options for key fobs, favoring makers that describe their shielding in detail. All were in stock for US delivery when we checked. Prices change often, so check the current price on each listing.
| Pick | Type | Holds | Best for |
|---|---|---|---|
| Mission Darkness Faraday Key Fob Bag (2-pack) | Pouch, 2-pack | One fob per bag (4.5 x 3 in inside) | Best overall |
| TICONN Faraday Bag for Car Key Fob (2-pack) | Pouch, 2-pack | One fob, 3 sizes | Budget |
| Samfolk Faraday Box with Faraday Bags | Box plus 2 pouches | 6 to 8 keys | Families |
| TICONN Faraday Box for Car Keys | Box | Up to 6 keys | A modern-looking box |
1. Mission Darkness Key Fob Bag: Best Overall
The Mission Darkness Faraday Key Fob Bag (2-pack) is the one pick whose maker names its test standards: it says shielding was confirmed to MIL-STD 188-125 and IEEE 299-2006, with full test reports available on request. It uses three layers of shielding fabric with paired seams, and you get two bags. The inside measures 4.5 by 3 inches, so measure a bulky key first. It had a 4.4-star average from about 3,000 ratings when we checked, and stock was running low.
2. TICONN Key Fob Bag: Best Budget Pouch
The TICONN Faraday Bag for Car Key Fob (2-pack) is the most-reviewed key fob pouch we found, with a 4.2-star average from more than 19,000 ratings. It comes in three sizes and has a separate outer pocket for cards. TICONN doesn’t name a test standard, so run the test at your car when it arrives.
3. Samfolk Faraday Box: Best for Families
The Samfolk Faraday Box with Faraday Bags is a wood and faux-leather box that the maker says holds 6 to 8 car keys, and it comes with two small pouches for when you’re out. It had a 4.5-star average from more than 13,000 ratings when we checked. Like any box, it only works with the lid fully shut.
4. TICONN Faraday Box: Best Modern-Looking Box
The TICONN Faraday Box for Car Keys has a carbon-fiber look and holds up to six keys with their keyrings, according to the listing. It had a 4.5-star average from about 1,400 ratings when we checked. It’s a good fit for an entryway tray or nightstand.
Our Verdict
If your car unlocks or starts without you pressing the fob, a Faraday pouch or box is one of the cheapest anti-theft steps you can take. Use a Mission Darkness bag or a TICONN pouch when you’re out, add a Samfolk box at home if you have several keys, and test both at your car. Then check your owner’s manual for a fob sleep mode, which costs nothing.
For more ways to protect your privacy and your things, see our roundup of privacy gadgets that actually work.
Staying at a hotel or rental? Protect your key, then check the room too, with our free one-page hidden camera checklist.
Frequently Asked Questions
Do Faraday bags work for key fobs?
A well-made one does. The bag is lined with conductive metal mesh that blocks the radio signal your fob gives off, so a relay device can’t pick it up. Cheap bags can leak through weak seams, so test yours: put the fob inside, walk up to your car, and check that the doors stay locked.
Is a Faraday box better than a pouch?
Neither blocks better by default. A box is easier at home because everyone can drop their keys in by the door. A pouch is better when you’re out. Many people use both, and some boxes come with pouches included.
How do I know if my Faraday bag is working?
Seal your fob inside and walk up to your car. If the doors don’t unlock and the car won’t start with the fob in the bag, the signal is blocked. Repeat the test every few months, because seams and linings wear out.
Can I put my key fob in the freezer or microwave instead?
No. The Associated Press reports that this doesn’t work like a Faraday bag, and you risk damaging your key. Use a pouch or box and test it at your car.
Do I need to protect my spare key?
Yes. Thieves can relay any working fob, so keep spares in a pouch or box too.
Can I turn off my key fob signal without a bag?
Some cars let you. Many Toyota fobs have a battery-saving mode: hold the lock button and press unlock twice, and the light blinks four times. Ford, Honda and Audi let you switch off keyless entry in the touchscreen menus on some models. Check your owner’s manual for your exact car.
Sources
- Associated Press (via KSL): Protecting your car from the growing risk of keyless vehicle thefts, with comments from Thatcham Research
- Product listings for the bags and boxes above, checked October 11, 2026
