A friend has one of these compact models from China, and it works just as you'd expect. It will completely kill any and all cell phone connections (or WiFi, or

A friend has one of these compact models from China, and it works just as you'd expect. It will completely kill any and all cell phone connections (or WiFi, or Bluetooth) within a large room. Apparently it can run for several hours on battery, or the length of a long movie.