: Efficient electromagnetic shielding: Multi-layer metal composite materials are used to effectively block wireless signals from electronic devices such as car keys and credit cards, prevent remote theft or signal interference, and provide more reliable security protection. Waterproof and fireproof design: The outer layer uses high-density waterproof fabrics, and the inner layer adds flame-retardant coatings to cope with daily splashing, rain and short-term high-temperature contact, protecting the safety of items in the bag. Anti-theft and anti-copying: By shielding RFID/NFC signals, car keys are prevented from being maliciously copied or hackers intercepting signals, while preventing magnetic stripe cards such as credit cards and ID cards from being demagnetized or information leaked. Lightweight material: Ultra-thin and lightweight design, easy to carry; wear-resistant and scratch-resistant fabrics extend service life, suitable for daily use or travel storage. Multifunctional applicability: Compatible with various electronic car keys (including keyless entry systems), access cards, bank cards, etc., one bag for multiple uses, it is a practical tool for personal privacy protection. Specification: Material: Cloth XS size: 14*9cm/5.46*3.51in Small size: 20*12cm/7.8*4.68in Medium size: 33*26cm/12.87*10.14in Large size: 43*38cm/16.77*14.82in Note: Due to different monitor settings and light conditions, the actual color of the item may vary slightly from the pictures. Thanks for your understanding! Please allow a 1-2 cm difference in measurements due to manual measuring. Package Content: 1/4 x Signal Blocking Bag