In the tunnel to Clinton’s vehicle after the debate, Secret Service used pointer flash lights pointing at the ground in front of Clinton’s feet (watch carefully) in order to guide Hillary through the tunnel to/into her vehicle,
Hillary entered the opposite (hidden side) of vehicle so the camera cannot see her entry.
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Pointer or Laser lights are used for Parkinson’s patients.
Dr. Ted Noel discussed pointers used for Parkinson’s patients in a recent video:
Note, Trump’s later departure through the tunnel to his vehicle was not accompanied by the use of such Secret Service pointer flash lights.