Transparency note: Frequency Blockers is an independent editorial site. We do not operate a testing lab, and we have not personally shielded every product we cover inside an anechoic chamber. Instead, we apply a rigorous, spec-based review framework that synthesizes manufacturer data, independent lab reports, verified buyer feedback, and deep domain research. Every recommendation on this site has passed all six checkpoints described below.
Why Spec-Based Reviews Matter
Most EMF and Faraday product reviews online fall into two camps: quick listicles that rehash manufacturer bullet points, or influencer posts that test a single scenario and call it a day. Neither approach serves you well.
Our spec-based framework goes deeper. We cross-reference attenuation claims against known testing standards (IEEE 299, MIL-STD-188-125), compare performance across frequency bands, and verify that real-world buyer experiences align with the numbers. When they diverge, we flag it.
Our 6-Point Review Framework
Every product we review must pass through these six evaluation checkpoints before it earns a recommendation.
1. Attenuation Specs Analysis
Attenuation, measured in decibels (dB), tells you how much signal a product blocks. We examine the full frequency range, not just a single headline number. A bag claiming 80 dB at 1 GHz may only deliver 40 dB at 6 GHz, and that matters for modern devices.
Here is what those numbers actually mean in practice:
| Attenuation (dB) | Signal Blocked | Real-World Meaning |
|---|---|---|
| 20 dB | 99% | Basic shielding, blocks most casual signals |
| 40 dB | 99.99% | Solid protection for phones and key fobs |
| 60 dB | 99.9999% | Professional-grade, meets most MIL-STD requirements |
| 80 dB | 99.999999% | Lab-grade isolation |
| 100+ dB | Virtually total | Government/military specification |
We pay special attention to performance at higher frequencies (5 GHz and above), because Wi-Fi 6E, 5G, and UWB car key systems all operate in those bands. A product with great low-frequency numbers but poor high-frequency performance may not protect modern devices.
2. Aggregate Buyer Review Synthesis
We analyze buyer reviews across Amazon, manufacturer sites, and independent forums. Rather than cherry-picking quotes, we look for recurring patterns: consistent praise, repeated complaints, and how the manufacturer responds to issues.
- Volume threshold: We generally require 50+ verified reviews before considering a product well-vetted by the market.
- Failure pattern detection: If multiple buyers report the same failure mode (zipper gaps, stitching failure, degraded shielding after months of use), we flag it regardless of the overall star rating.
- Recency weighting: Recent reviews carry more weight. Manufacturers sometimes change materials or suppliers, and a product with great 2023 reviews may have quality issues in 2026.
3. Material and Certification Research
We research the shielding materials used (copper, nickel, silver, conductive fabric blends) and verify any claimed certifications. Key things we look for:
- Testing standards: IEEE 299 (shielding effectiveness measurement), MIL-STD-188-125 (HEMP protection), and ASTM D4935 (planar materials).
- Lab reports: Products backed by third-party lab test reports score higher in our framework. We link to these reports when publicly available.
- Material longevity: Some conductive coatings degrade with washing or UV exposure. We research durability claims and note when a product may lose effectiveness over time.
4. Use-Case Fit Assessment
A Faraday bag for car keys has different requirements than a laptop sleeve or a full phone pouch. We evaluate each product against its intended use case:
- Key fob protection: Must block LF (125 kHz), UHF (315/433 MHz), and UWB (6-8 GHz) to prevent relay attacks.
- Phone pouches: Must block cellular, Wi-Fi, Bluetooth, GPS, and NFC across a wide frequency range.
- Laptop sleeves: Need sufficient size, padding for physical protection, and effective shielding.
- Large enclosures: Evaluated for seal integrity, access convenience, and shielding consistency across the enclosure.
5. Price-to-Value Ratio
EMF protection products range from under $10 to several hundred dollars. We compare price against shielding performance, build quality, included features (multiple pouches, window pockets, locking mechanisms), and warranty terms to identify true value.
An expensive product is not automatically better. We have found mid-priced options that match or exceed the shielding specs of premium alternatives.
6. Brand Reputation and Support
We consider the track record of each manufacturer: how long they have been in the EMF shielding space, whether they publish transparent test data, how they handle warranty claims, and whether they have a history of accurate (not inflated) marketing claims.
Why Independent Lab Tests Are the Gold Standard
When a product has been tested by an accredited third-party lab (such as Keystone Compliance, Elite Electronic Engineering, or similar facilities), that data carries more weight in our reviews than manufacturer self-reported specs.
Third-party labs use calibrated equipment inside shielded chambers, testing across a standardized range of frequencies. Their results are repeatable and comparable across products. When these reports are available, we reference them directly and note any discrepancies with manufacturer claims.
We are transparent when lab data is not available for a product. In those cases, we rely more heavily on the other five checkpoints in our framework and note the absence of independent verification.
What We Do Not Do
In the interest of full honesty:
- We do not operate our own RF testing lab.
- We have not personally tested every product inside a shielded chamber.
- We do not accept payment from manufacturers in exchange for positive reviews.
- We do not guarantee that any product will perform identically to its published specs in every real-world scenario, because environmental factors (nearby structures, signal strength, device orientation) affect results.
Affiliate Disclosure
Frequency Blockers participates in affiliate programs. When you purchase a product through our links, we may earn a commission at no additional cost to you. This does not influence our review process: products that fail our 6-point framework are not recommended, regardless of affiliate potential.
For our complete affiliate disclosure, see our Affiliate Disclosure page.
Corrections and Updates
If you are a manufacturer and believe we have made a factual error about your product, or if you have lab test data you would like us to consider, please contact us. We will review the evidence and update our content promptly if a correction is warranted.
Readers: if you have first-hand experience that contradicts our review of a product, we want to hear about it. Our goal is accuracy, and real-world feedback makes our reviews better.
Last updated: February 2026