Designed to block the wireless signal from your car key.
 
This prevents thieves from standing at your front door with a "repeater device" to read and then extend your wireless car key to open and start your car. 
Block wireless signal from your car key that opens the car and allows start. Prevention of Relay Attack to clone your wireless car key, prevent theft. RFID Protector. Decrease likelihood of unauthorised entry by storing your key in this Faraday cage holder which blocks electromagnetic transmissions.
 
They have the ability to clone your wireless car key but with this RFID Protector, when your key is stored, all wireless signals are blocked.
 
This has been fully tested in a Tesla Model S on the windscreen and even next to where the wireless beacon is inside the Tesla Model S, in the centre arm console.
 
The Tesla still couldnt see the key, also applicable for the Tesla Model X.
 
Works in the same way as a "faraday cage" and also works with Mercedes, BMW, Audi, etc Keyless entry.