Abstract: A safety device for use with a toy guns, less-lethal guns (such as non-powdered guns) and lethal guns detects motion of the gun, and causes light emitting diodes or other light sources incorporated into the gun to prominently flash. The flashing light sources alert bystanders in a way that distinguishes lethal firearms from toy guns and less-lethal guns. The flashing diodes can also be activated when the gun is armed, cocked or otherwise ready to be fired. Motion is detected through the use of an electric circuit that includes a spring, an oscillating mass, and a ring adapted to surround the oscillating mass.