It's a wonder that the French government has not (yet) decided to make this product mandatory for all motorcycle riders, the same way they are making hi-viz clothing mandatory.
But there are a lot of bikers out there who want to be sure they are seen, particularly at night, so this product may be of use to them. The product, called "Fibre Flare MVP" (MVP stands for Maximum Visibility Protection) is a battery powered fibre tube that is fixed to the rear of your helmet. You can mount it horizontal or vertically.
The fibre tube lights up like a neon tube, thanks to the onboard 4 x AAA batteries. It has only one color, but you have the choice in several of them (red, green and yellow). You do have the choice of making the light stay on continuous, or blinking. The batteries will last 30 hours or 80 hours respectively.