The best car key signal blockers
A relay attack copies your key's signal through your front door. A six-dollar pouch stops it — if it works, which no maker here publishes a number to prove. So here is how to check yours.
By Sawyer V. · Published · How we research
We have not tested any of this. Everything below is compiled from published manufacturer specifications, and the arithmetic is printed so you can check it. This page carries affiliate links: if you buy through one we earn a commission at no extra cost to you, and it does not change the order of the picks. Full disclosure.
The verdict
Buy the Lanpard double-layer 2-pack at $12.99 if you want the one product here that publishes how it is built, or the TICONN 2-pack at $5.99 if you would rather spend six dollars and test it yourself. Those are the only two sensible positions, because not one pouch in this category publishes a signal attenuation figure in decibels — the single specification that would let you compare them. Lanpard at least states two layers of carbon fiber shielding. Prices as of October 6, 2026.
Then run the test, whichever you buy. Put the key in the pouch, seal it, walk to the car and pull the door handle. If it opens, the pouch does not work and you have learned that for free in thirty seconds. Repeat it once a month, because the shielding fabric in these creases and wears.
| # | Pick | Install | Score | Price |
|---|---|---|---|---|
| 1 | Lanpard Double-Layer Faraday Bag for Key Fob, 2 Pack The only published shielding construction here | Drops in | 8.8/10 | $12.99 - view on Amazon |
| 2 | Faraday Box with 2 Faraday Bags A box for the hallway plus pouches for the pocket | Drops in | 8.2/10 | $18.39 - view on Amazon |
| 3 | TICONN Faraday Bag for Car Key Fob, 2 Pack Two pouches for the price of a coffee | Drops in | 8.2/10 | $5.99 - view on Amazon |
| 4 | Vammcht Faraday Bag for Key Fob, 2 Pack Skip it -- premium wording, no published specification | Drops in | 8.2/10 | $7.10 - view on Amazon |
Prices last verified October 7, 2026. They move constantly; the figure on Amazon when you click is the real one.
What a relay attack actually is
A keyless-entry car is constantly asking "is my key nearby?" The key answers when it hears the question. Neither side checks how far away the other really is — only whether the conversation happens.
A relay attack exploits that with two devices and two people. One stands near your front door, picks up the faint signal from the key on the hall table, and relays it to a second device standing beside your car. The car hears what it thinks is its key, unlocks, and in a pushbutton-start car it will also start.
What a pouch stops, and what it does not
Be precise about this, because the category oversells itself.
| Threat | Pouch helps? | What actually helps |
|---|---|---|
| Relay attack on a keyless-entry car | Yes | — |
| Someone reading your key through a door or window | Yes | — |
| Key cloning from the OBD2 port | No | A port lock, or a steering wheel lock |
| Theft of an older car with a metal key | No | A steering wheel lock |
| Catalytic converter theft | No | Nothing in this category |
| Breaking a window for items in the cabin | No | Leave nothing visible |
| Tracking a car that has already been taken | No | A hidden GPS tracker |
Three of those rows point somewhere else on this site. A steering wheel lock is the visible deterrent that works regardless of how the car is entered. A GPS tracker is what you want after the fact. And a car safe addresses the smash-and-grab that has nothing to do with your key.
The specification nobody publishes
Shielding effectiveness is measured in decibels of attenuation, across a stated frequency range. A key fob typically talks in the 315 to 433 MHz region and listens on a low-frequency band, so a useful figure would cover both.
Not one of the four products here publishes an attenuation figure, a frequency range or a test standard. Three of the four do not publish a layer count either. What you get instead is the words anti-theft, premium and upgraded, none of which is a number.
That is a genuine gap, and it is why this page leans so hard on the self-test. In a category with no published specification, the thirty-second test at your own car is better evidence than anything on the box.
The test, in detail
- Put the key fully inside and close the seal properly. These use a fold-over flap with hook-and-loop or a magnetic closure. A gap is a hole in the shield
- Walk to the car with the pouch in your hand. Not in a bag, not in a pocket with other things
- Touch the door handle the way you normally would. On most keyless cars the handle has a capacitive sensor that triggers the handshake
- Try the start button too, if the car is unlocked and the pouch is inside the cabin. The interior antenna is usually stronger than the door one, so this is the harder test
- If nothing responds, it works. If anything does, the pouch has failed and it is six dollars you can stop relying on
Repeat it monthly. The shielding in these is a metalized fabric layer, and the one thing that defeats metalized fabric is being folded, creased and shoved in a pocket every day. They wear out silently.
The four, on what they publish
| Product | Shielding layers | Material | Attenuation | Contents | Price |
|---|---|---|---|---|---|
| Lanpard double-layer | 2 | Carbon fiber, stated | Not published | 2 pouches | $12.99 |
| TICONN | Not published | Not published | Not published | 2 pouches | $5.99 |
| Faraday box + bags | Not published | Not published | Not published | 1 box, 2 pouches | $18.39 |
| Vammcht | Not published | Not published | Not published | 2 pouches | $7.10 |
Who each one is for
- Lanpard double-layer — anyone who wants a published construction. Two layers of carbon fiber shielding, stated, which is more than anything else here says. Two pouches, so the spare key is covered. Skip it if you would rather test a six-dollar pouch than pay double for a layer count
- TICONN — the sensible default. Six dollars for two pouches from a brand that sells a lot of them. In a category with no published specification, the cheapest pouch that passes the handle test is the right pouch. Skip it if you want to know how it is built
- Faraday box and bags — the right shape for the actual problem. The attack happens overnight against the key near your front door, so a box in the hall is the mitigation that does not depend on you remembering a pouch. Skip it if you only ever want something pocket-sized
- Vammcht — nobody. See the skip note
Two things people get wrong
The spare key. Shielding the key you use and leaving the spare in a drawer by the door defeats the entire exercise, because a relay attack does not care which key it hears. This is why every pick here is a two-pack or a box-and-pouches bundle: you need both keys covered, every night.
The pouch you stop using. A pouch only works when the key is in it. The common failure is not technical — it is that putting the key away becomes one more step and the habit lasts three weeks. A box by the door that the keys get dropped into survives better than a pouch you have to remember to seal, which is the practical argument for the bundle.
The rest of keeping a car where you left it
A signal blocker addresses one specific, increasingly common attack. Two other things address the rest.
A steering wheel lock is the only item in this family a thief can see from outside the car, which is the point of it — it moves the problem to somebody else's car before any of this starts. See best steering wheel locks. And if a car does go, location is the only thing that gets it back — best car gps trackers.
If the car lives on a street rather than a driveway, the broader set of problems that comes with that is in best car accessories for no garage.
Every pick, with the working
Each entry lists the specifications the maker publishes, the axis scores those specifications produce, and what you give up. Rows that read “Not published” are not omissions on our side: they are things the maker will not commit to in writing, and they cost the product points on the transparency axis. Specifications compiled September 4, 2026.
Our pickThe only published shielding construction here
Lanpard Double-Layer Faraday Bag for Key Fob, 2 Pack
Two layers of carbon fiber shielding material, published, which is more than any other pouch in this group says about how it works. Layer count is a weak proxy for attenuation and it is the only proxy available, because nobody in this category publishes a decibel figure. Two pouches, so the spare key gets one too -- which matters, since a relay attack only needs the key you left in the hall.
- Shielding layers
- 2
- Shielding material
- Carbon fiber, stated
- Pack quantity
- 2 pouches
- Blocks
- RFID key fob signal, stated
- Attenuation (dB)
- Not published
- Frequency range
- Not published
- Dimensions
- Not published
- Warranty
- Not published
List price $12.99 per Amazon listing, October 6, 2026, captured on the compile date below. Not a live price and not what you will pay — the button is where the real number is.
What it gets right
- Double-layer shielding published, with the material named as carbon fiber
- Two pouches per pack, so the spare key is covered as well
- Describes itself as a Faraday cage rather than only an RFID blocker
Flaws
- No attenuation figure in dB, and no frequency range stated
- Dearest pouch-only option here at the price captured
- No published dimensions, so fitting a large fob is a guess
The working behind the 8.8
- Heat headroom: not scored (weight 22%)
- The maker publishes no operating-temperature ceiling, so this axis is dropped and the other weights are re-normalized.
- Install effort: 10.0 (weight 24%)
- Drops in and sits there. No fixing of any kind, and it comes out again when you sell the car.
- Price against the ceiling: 10.0 (weight 24%)
- Listed at $12.99 on the compile date. This site's buyer has a practical ceiling around $150 for a single upgrade, so the scale rewards everything under $100 and falls away sharply past $150. The live price is very often different, and that is what the button is for.
- Written commitment: not scored (weight 15%)
- No warranty term published, so this axis is dropped and the other weights are re-normalized.
- Spec transparency: 5.0 (weight 15%)
- 4 of the 8 specifications we went looking for are published by the maker (50%). A blank row is never a guess here: it prints “Not published” and it costs the product points, because a figure nobody will commit to in writing is a figure you cannot check.
Axes with no published input are dropped and the remaining weights re-normalized, so a product is not punished for a category where an axis does not apply. Specifications compiled September 4, 2026 from the Lanpard double-layer Faraday bag listing.
2A box for the hallway plus pouches for the pocket
Faraday Box with 2 Faraday Bags
A box and two pouches, which is the right shape for the actual problem. A relay attack happens overnight, from the pavement, against the key on the hall table near the front door -- so the box is where the key lives at home and the pouches are for the days you want it shielded out of the house. Buying both separately costs more; nothing here is published about the shielding in either.
- Contents
- 1 box and 2 pouches
- Blocks
- Key fob signal, stated
- Shielding layers
- Not published
- Shielding material
- Not published
- Attenuation (dB)
- Not published
- Frequency range
- Not published
- Dimensions
- Not published
- Warranty
- Not published
List price $18.39 per Amazon listing, October 6, 2026, captured on the compile date below. Not a live price and not what you will pay — the button is where the real number is.
What it gets right
- Covers the overnight case with a box and the out-of-house case with pouches
- Cheaper than buying a comparable box and two pouches separately
- A box is harder to forget than a pouch, which is the real failure mode
Flaws
- No shielding layers, material or attenuation published for box or pouches
- Unbranded, with no published warranty
- Dearest item here, and the box only helps at home
The working behind the 8.2
- Heat headroom: not scored (weight 22%)
- The maker publishes no operating-temperature ceiling, so this axis is dropped and the other weights are re-normalized.
- Install effort: 10.0 (weight 24%)
- Drops in and sits there. No fixing of any kind, and it comes out again when you sell the car.
- Price against the ceiling: 10.0 (weight 24%)
- Listed at $18.39 on the compile date. This site's buyer has a practical ceiling around $150 for a single upgrade, so the scale rewards everything under $100 and falls away sharply past $150. The live price is very often different, and that is what the button is for.
- Written commitment: not scored (weight 15%)
- No warranty term published, so this axis is dropped and the other weights are re-normalized.
- Spec transparency: 2.5 (weight 15%)
- 2 of the 8 specifications we went looking for are published by the maker (25%). A blank row is never a guess here: it prints “Not published” and it costs the product points, because a figure nobody will commit to in writing is a figure you cannot check.
Axes with no published input are dropped and the remaining weights re-normalized, so a product is not punished for a category where an axis does not apply. Specifications compiled September 4, 2026 from the Faraday box and bag bundle listing.
3Two pouches for the price of a coffee
TICONN Faraday Bag for Car Key Fob, 2 Pack
Six dollars for two pouches from a brand that sells a lot of them. It states that it blocks NFC and RFID and stops there -- no layer count, no material, no attenuation figure. At this price that is a reasonable trade, because the test that matters takes thirty seconds and you can run it yourself: put the key in, walk to the car, pull the handle. If the door opens, the pouch does not work.
- Pack quantity
- 2 pouches
- Blocks
- NFC and RFID, stated
- Shielding layers
- Not published
- Shielding material
- Not published
- Attenuation (dB)
- Not published
- Frequency range
- Not published
- Dimensions
- Not published
- Warranty
- Not published
List price $5.99 per Amazon listing, October 6, 2026, captured on the compile date below. Not a live price and not what you will pay — the button is where the real number is.
What it gets right
- Cheapest option here, and you get two pouches
- States NFC and RFID blocking explicitly
- A brand with a large catalog rather than a one-listing seller
Flaws
- No shielding layer count or material published
- No attenuation figure and no frequency range
- No published dimensions
The working behind the 8.2
- Heat headroom: not scored (weight 22%)
- The maker publishes no operating-temperature ceiling, so this axis is dropped and the other weights are re-normalized.
- Install effort: 10.0 (weight 24%)
- Drops in and sits there. No fixing of any kind, and it comes out again when you sell the car.
- Price against the ceiling: 10.0 (weight 24%)
- Listed at $5.99 on the compile date. This site's buyer has a practical ceiling around $150 for a single upgrade, so the scale rewards everything under $100 and falls away sharply past $150. The live price is very often different, and that is what the button is for.
- Written commitment: not scored (weight 15%)
- No warranty term published, so this axis is dropped and the other weights are re-normalized.
- Spec transparency: 2.5 (weight 15%)
- 2 of the 8 specifications we went looking for are published by the maker (25%). A blank row is never a guess here: it prints “Not published” and it costs the product points, because a figure nobody will commit to in writing is a figure you cannot check.
Axes with no published input are dropped and the remaining weights re-normalized, so a product is not punished for a category where an axis does not apply. Specifications compiled September 4, 2026 from the TICONN 2-pack Faraday bag listing.
4Skip it -- premium wording, no published specification
Vammcht Faraday Bag for Key Fob, 2 Pack
Skip this one. Upgraded and premium are the two load-bearing words in the listing and neither is a specification. It publishes nothing the cheaper TICONN pack does not, and the Lanpard pouches publish a layer count and a shielding material for about a dollar more.
Upgraded and premium are the two load-bearing words in this listing, and neither is a specification. It blocks RFID, it comes in a two pack, and there is nothing else to compare. For a dollar more the Lanpard pouches publish a layer count and a shielding material; for a dollar less the TICONN pack says the same amount about itself for less money.
- Pack quantity
- 2 pouches
- Blocks
- RFID key fob signal, stated
- Shielding layers
- Not published
- Shielding material
- Not published
- Attenuation (dB)
- Not published
- Frequency range
- Not published
- Dimensions
- Not published
- Warranty
- Not published
List price $7.10 per Amazon listing, October 6, 2026, captured on the compile date below. Not a live price and not what you will pay — the button is where the real number is.
What it gets right
- Two pouches per pack
- States RFID signal blocking
Flaws
- Upgraded and premium are claims, not specifications
- No layer count, material, attenuation figure or dimensions published
- Sits between two pouches that are either cheaper or better documented
The working behind the 8.2
- Heat headroom: not scored (weight 22%)
- The maker publishes no operating-temperature ceiling, so this axis is dropped and the other weights are re-normalized.
- Install effort: 10.0 (weight 24%)
- Drops in and sits there. No fixing of any kind, and it comes out again when you sell the car.
- Price against the ceiling: 10.0 (weight 24%)
- Listed at $7.1 on the compile date. This site's buyer has a practical ceiling around $150 for a single upgrade, so the scale rewards everything under $100 and falls away sharply past $150. The live price is very often different, and that is what the button is for.
- Written commitment: not scored (weight 15%)
- No warranty term published, so this axis is dropped and the other weights are re-normalized.
- Spec transparency: 2.5 (weight 15%)
- 2 of the 8 specifications we went looking for are published by the maker (25%). A blank row is never a guess here: it prints “Not published” and it costs the product points, because a figure nobody will commit to in writing is a figure you cannot check.
Axes with no published input are dropped and the remaining weights re-normalized, so a product is not punished for a category where an axis does not apply. Specifications compiled September 4, 2026 from the Vammcht 2-pack Faraday bag listing.
Prices last verified October 7, 2026. They move constantly; the figure on Amazon when you click is the real one.
Questions people actually ask
Do Faraday pouches for car keys actually work?
A working one does, and you can prove it in thirty seconds: seal the key inside, walk to the car, pull the handle. If nothing happens it works. The problem with the category is that no pouch here publishes an attenuation figure in decibels, so the self-test is better evidence than anything printed on the packaging.
What is a relay attack on a car?
Two devices and two people. One picks up the faint signal from your key inside the house and relays it to the second, standing by your car. The car hears what it believes is its own key, unlocks, and on a pushbutton-start car will start. Neither the car nor the key checks the real distance between them.
Do I need to shield both car keys?
Yes. A relay attack does not care which key it hears, so a shielded key plus a spare in the hall drawer leaves you exactly as exposed as before. Every pick on this page is a two-pack or a box-and-pouch bundle for that reason.
Is a Faraday box better than a pouch?
For overnight, yes — not because it shields better, but because dropping keys into a box by the door is a habit that survives, and sealing a pouch every night often is not. The attack happens overnight against the key near your front door, so the box covers the case that matters most.
Will a signal blocker stop my car being stolen?
It stops one specific attack. It does nothing about key cloning through the OBD2 port, theft of an older car with a metal key, a window broken for something on the seat, or recovering a car that has already gone. A steering wheel lock and a hidden tracker cover different parts of the same problem.
Sources
- Published double-layer carbon fiber shielding and pack quantity for the Lanpard Faraday bag
- Published NFC and RFID blocking claim and pack quantity for the TICONN Faraday bag
- Published contents for the Faraday box and Faraday bag bundle
- Published RFID blocking claim and pack quantity for the Vammcht Faraday bag