Every Faraday bag, uses GoDark RF-shielding fabric that has passed the MIL-STD-188-125-2 test, a standardized military test for the EMP-shielding effectiveness of small transportable containers. The anti-tracking GoDark RF material effectively blocks signals and secures your digital devices from data theft, unauthorized access, and location tracking. We also chose a tailor-made roll-top design because we believe it provides the best failure-free signal-blocking closure on the market. The GoDark Vault protects your car from fob relay theft by blocking all EMF signals to or from your keyless remote or key fob, preventing car theft.