The par-4 12th hole at Nags Head Golf Links on North Carolina's Outer Banks uses a callbox-type warning device. After teeing off, players push a red button to indicate that they are in the landing area, which is hidden from view. When exiting the danger zone, players indicate that the following group can proceed safely by pushing the green button on a second box that's located on the right side of the fairway and connected to the box on the tee.