from GBPPR

A silent drill is a device for quietly drilling holes into walls, doors, floors, etc. for the insertion of a technical surveillance device. For instance, say a $2600 meeting was taking place in a hotel room. To protect your family and their privacy, you may wish to monitor this meeting. First, you’d arrange to rent the hotel room next to the room where the meeting is taking place. Then you would silently drill a hole through the wall in your room, and just before reaching the outside wall into the meeting room, you’d reduce the size of the drill bit so the final hole going into the meeting room is only the size of a pin-hole. You could then place a microphone or even a video camera into the hole and capture any activity coming from the meeting room.