What Is a Faraday Bag and How Does It Work?
A Faraday bag is a portable, sealed enclosure that blocks all electromagnetic signals from entering or leaving the bag. The principle is the same as a Faraday cage: a conductive shell surrounds the device on all sides, preventing electric fields and radio-frequency signals from passing through. DefenderShield Faraday bags use multiple layers of Ultra Armor® shielding material to create this enclosure in a soft, portable format. When the bag is sealed, your device cannot send or receive any signal — no calls, no data, no GPS, no Bluetooth, no RFID.
How Is a Faraday Bag Different from an EMF Phone Case?
An EMF phone case provides directional shielding: it blocks EMF between the phone and your body while keeping the phone connected and functional. A Faraday bag provides total isolation: the device is completely cut off from all wireless communication. Your phone cannot ring, transmit location data, or be accessed remotely while inside a sealed Faraday bag. These are different tools for different situations — a phone case is for daily EMF reduction during use, while a Faraday bag is for complete signal isolation during storage or travel.
Why Signal Isolation Matters
Modern devices transmit continuously. Even when idle, a smartphone maintains active connections to cellular towers, Wi-Fi networks, and Bluetooth peripherals — each of which transmits your location and device identity. A laptop connected to Wi-Fi is accessible to remote exploits. A keyless-entry fob broadcasts a signal that can be relayed by thieves to unlock and start your car from a distance. A Faraday bag eliminates all of these vectors simultaneously by removing the device from the wireless environment entirely.
ConcealShield® Cell Phone Faraday Bag — A compact, sealed pouch that completely isolates your phone from all wireless signals. Available in Standard (compact pouch with VELCRO® closure) and Crossbody (multiple pockets with crossbody strap) configurations. The front pocket can hold your phone with directional EMF protection while still receiving a signal — the sealed main compartment provides full isolation. Best for: travel, airports, privacy-sensitive meetings, anti-surveillance, and situations where you need your phone physically present but digitally invisible.
Laptop & Tablet Faraday Bag — A portable Faraday sleeve sized to fit laptops up to 16.5” (physical dimensions up to 14.75” × 10” × 1.5”), with room for tablets, multiple smartphones, external hard drives, smart home devices, and small cameras. The leakproof VELCRO® closure creates a full-perimeter seal for complete signal isolation. Built with water-resistant military-grade ballistic nylon exterior and independently tested to MIL-STD-461G for EMP and CME compliance. Best for: executive travel, law enforcement, field operations, EMP preparedness, and anyone storing sensitive devices in public or transit environments.
Key Fob Faraday Bag — A small sealed pouch with a leakproof VELCRO® closure, designed specifically for car key fobs and smart keys. Water-resistant military-grade ballistic nylon exterior. Blocks the relay signal that thieves use to intercept and amplify your key fob’s transmission to unlock and start your vehicle remotely. Best for: Key fobs and key cards for cars, homes or other secure locationsIf you need EMF protection while using your phone, a Faraday bag is not the right product — use an EMF phone case or shield instead. If you need complete signal isolation for privacy, cybersecurity, or EMP defense, start with the ConcealShield for your phone.
Tips for Effective Faraday Bag Use
Seal the bag completely each time. A partially open Faraday bag is not a Faraday cage — even a small gap allows signals to enter and exit. For the Laptop Faraday Bag, press firmly along the entire VELCRO® length including corners.
Test your bag periodically by calling your phone while it is sealed inside. If the call connects, the seal may need adjustment or the bag may need replacement. For a more precise check, use a free RF meter app before and after sealing and confirm readings drop to zero.
For EMP preparedness, store critical electronics inside the Faraday bag when not in use. The multi-layer construction protects against electromagnetic pulse events that could damage vulnerable electronics.
When traveling through airports or border crossings, a sealed Faraday bag prevents remote access to your device, protecting against RFID skimming, Bluetooth exploits, and location tracking.
Faraday Bag FAQ
1. Does a Faraday bag block all signals, including 5G?
Yes. DefenderShield Faraday bags block all wireless communication signals when properly sealed, including cellular (1G–5G), Wi-Fi, Bluetooth, GPS, RFID, NFC, and radio frequencies. Ultra Armor® shielding provides up to 99% RF attenuation across 300 Hz–110 GHz, covering the full 5G spectrum, including mmWave bands, which many other bags cannot block. All Ultra Armor Faraday Bags additionally block VHF, UHF, HF, and satellite signals.
2. Can I receive calls or messages while my phone is in the Faraday bag?
No — not when the device is in the sealed main compartment. That is the purpose of the bag: your phone is completely isolated from all networks. Calls, texts, and data will not reach the device. Any missed activity will appear once you remove the phone from the bag and it reconnects. The ConcealShield’s front pocket provides directional EMF shielding from your body while keeping the phone connected, if you need that option.
3. Will the Faraday bag protect my device from an EMP?
DefenderShield Faraday bags are constructed with multiple layers of advanced shielding materials designed to protect electronics from EMP (electromagnetic pulse) and CME (coronal mass ejection) events. Our Faraday Bags have been independently tested to MIL-STD-461G — the US military standard for electromagnetic compatibility — for EMP and CME compliance. Test documentation is available on request.
4. What is the difference between the Standard and Crossbody ConcealShield?
Both use the same Ultra Armor® shielding and provide the same signal isolation. The Standard version is a compact pouch. The Crossbody version includes multiple pockets and an adjustable crossbody strap for hands-free carry during travel.
5. Can I use a Faraday bag to prevent car key fob relay theft?
Yes. The Key Fob Faraday Bag blocks the signal your key fob emits, preventing thieves from using relay devices to intercept and amplify that signal. Place your key fob in the sealed bag when parked — your vehicle cannot be unlocked or started via relay attack while the fob is inside.
6. What is the return policy?
DefenderShield offers a 30-day return window with a full refund on unused products if you are not satisfied with your purchase. All Faraday bags include a 1-year manufacturer warranty covering material defects and shielding performance. See full returns policy
7. Are DefenderShield Faraday bags HSA/FSA eligible?
Yes. DefenderShield Faraday bags and health-related accessories are HSA/FSA eligible. Visit for details on how to apply your health savings or flexible spending account at checkout.
