Updated October 2026.
The best Faraday bag for car keys is the one you'll actually use every time: a leather pouch on your keyring if you carry the fob, or a box by the front door if the keys live there overnight. Any of them stops keyless relay theft only while the fob is fully inside and closed — so check yours at the car the day it arrives.
What Actually Stops Relay Theft
Keyless-entry systems read your key fob's signal from a short distance so you can unlock and start the car without pressing a button. Relay theft exploits that: one thief stands near your house with a device that picks up the fob's signal, a second stands next to your car, and together they pass the signal along so the car thinks the key is right there. It takes seconds.
The fix is to stop the fob being reachable when you're not using it. A Faraday pouch or box fully encloses the fob in a conductive shield, so there's nothing for a relay device to pick up.
Does Your Car Even Need One?
Most keyless cars do. Some newer models use ultra-wideband (UWB) keys, which measure distance precisely and resist relay attacks; others let you switch keyless entry off or put the fob to sleep. Check your car first — if it has UWB or a fob sleep mode, you may not need anything. Our relay theft data page shows how common the attack is.
Pouch or Box?
| Pouch (leather or fabric) | Box | |
|---|---|---|
| Best for | Carrying the fob with you | Keys left by the door overnight |
| Holds | One fob (most pouches) | Several fobs — a household's worth |
| Ease of use | Clip-on, fold or Velcro closure | Drop in, close the lid — one hand |
| Weak point | Closure left half open | Lid not fully shut |
Our Options
- Leather key fob pouches — hand-stitched leather with a signal-blocking lining, clip onto your keys; black, brown, dark grey or a 2-pack for two cars.
- RFID key case — a small fabric case in four colors, the lowest-cost single-fob option.
- Universal signal-blocking pouch — sized for a phone or a key fob, if you want one pouch for both.
- Fire-resistant multi-size pouch — fiberglass outer in four sizes, from fob-size up to tablet-size.
- Faraday box for car keys (two sizes) and the family-size box (about 5–6 fobs) — for the hall table.
How to Test It (2 Minutes)
- Put the fob inside and close the pouch or lid completely — no key ring trapped in the closure.
- Walk to the car and try the door handle, then the push-start if you can reach it. Nothing should happen.
- Take the fob out and try again to confirm the car responds normally.
- Repeat with your spare fob, and re-test every few months — closures and linings wear.
What It Won't Stop
- OBD-port attacks (programming a new key inside the car)
- Key cloning, towing or a plain break-in
- Theft while the fob is out of the pouch — it only works when it's in
Questions
Do Faraday pouches for key fobs really work?
A sealed pouch with an intact lining blocks the fob's signal, which is what relay theft needs. The door-handle test above shows whether yours does.
Can I put two fobs in one pouch?
Only if the closure still shuts flat. Most leather pouches are sized for one fob; for two or more, use a box.
Does aluminum foil or a microwave work?
Foil can, but it tears and is easy to leave with gaps. Microwaves and fridges often don't block car fobs — test before relying on one. Instructions for a DIY pouch or tin are in our DIY guide.
Will it affect my fob's battery?
The pouch has no power and doesn't interact with the battery; the fob simply can't talk to the car while it's inside.
Compare everything side by side in Faraday bags and boxes for car keys.
