The bulbs have LEDs on the side and illuminate backwards. It seems that they are designed for light fixtures that have reflectors, so they do not fit all cars, caution is needed. I put them side by side with a "classic" incandescent bulb and the incandescent bulb was slightly brighter.

So if you are interested, make sure first of all that you have light fixtures with a mirror (e.g. usually the rear lights do not have).