A rear fog light mounts on the rear of a vehicle to help it be more visible to drivers behind you. Regulations in most of the world permit vehicles to be equipped with one or two rear fog lights. If only one rear fog is equipped, it must be on the driver’s side of the vehicle. Having two is legal but makes it much more difficult for drivers behind you to see your brake lights. If the vehicle doesn't have a rear fog light, flash your brake lights periodically by applying the brake pedal. This will help motorists behind you to see your vehicle in heavier fog.
