Protect your privacy: The Faraday bag protects against hackers' RFID readers in the range of 10 kHz to 30 GHz. Signal blocking bag: The inner layer blocks signals, the black leather exterior makes the bag look normal. Convenient to use: Storing ID cards, bank cards and other magnetic cards in the Faraday bag can prevent the magnetic function and stored information from being lost. Dimensions: 20 x 10 x 1.5 cm Faraday bag for keychain: The bag blocks GPS and car key signals to prevent tracking and protect your car's security system from hacker attacks. Note: The data is all measured manually, please allow 1-3 cm error due to light and display difference, there may be color difference, please refer to the actual item received.