Wi-Fi Blocking Wallpaper

A British defense contractor has developed a new type of wallpaper that blocks Wi-Fi signals while still letting through cellphone signals.

The wallpaper is designed as a security method for stopping people outside a building connecting to Wi-Fi routers within the building.

The wallpaper contains a very thin sheet of kapton plastic coated in copper and costs about $100 per square foot.

What I want to know is… if they put this on the walls how do they stop the Wi-Fi leaking out through the doors and windows??

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