It is known as the Forever Flashlight and it’s famous because of its capability to function with no batteries.
This means no money spent on batteries and you can be sure that if you are in a dark environment you’ll have the “guiding light” that never fades, because this flashlight is designed to last forever, as its name suggests.

Working based on Faraday Principle of electromagnetic energy, the Forever Flashlight spreads very bright LED light around after you shake it for about 25 seconds.
Michael Faraday’s Principle was adapted so that shaking causes an internal magnet to pass repeatedly through a metal coil, setting up an electric current that powers the white LED, and the bright light is seen as the flashlight’s body is translucent.

You could use it as an emergency flashlight or in different occasions as you probably won’t have the mood to shake it over and over again to obtain just 5 minutes of light, although the light is very bright and LEDs never need replacement.
More than that, the Forever Flashlight is waterproof and is made of a special material that lets it float on the water in case you drop it.