--- Rough Internal size : 17 cm x 9.8 cm x 1.4 cm --- (we fit both our main car key and spare in one pouch). --- Many modern cars use keyless entry technology, allowing for remote access to the vehicle and its ignition. --- The Defender Signal Blocker is lined with specialist RPF material preventing your key fob from communicating with your vehicle. --- This product blocks radio signals as well as passive RFID including calls, SMS, Wi-Fi, Bluetooth, RFID, 4G and NFC. --- Defender Signal Blocker - Mobile phone blocking signal jamming pouch with RPF for road safety and RFID blocking car fob protection. Color: Black.