Forever Lights are a great, brilliant invention. In fact, any invention that uses alternative forms of energy are wonderful; hand-cranks, solar cells, magnets. Forever Lights—and their knock-offs—are flashlights which use one or more super-bright white LEDs instead of incandescents, which allow it to create pure, white (or bluish) light that remains cool and does not create heat, while also lasting—for all intents and purposes—forever without fear of burning out. Furthermore, Forever Lights use rechargeable lithium ion batteries instead of single-shot alkalines. Finally, the rechargeable batteries are recharged, not by plugging it into an outlet, but by simply shaking it. They have a powerful magnet inside which when shaken, passes through a tightly coiled wire. The magnetic field from the magnet passing through the coil creates electricity which charges the batteries.
To top it all off, if you get a good one (knock-offs are of poorer quality) they will also be waterproof. This makes these perfect for underwater use like in scuba diving or cave diving. A problem that many divers have feared is their flashlight batteries dying while they are down there (or other cave spelunkers above ground). With this, they just shake it a bit and they’ve got light again; wonderful. Nicer models even allow you to choose from using a single LED for less light up to three for a whole lot of light.
This is truly a brilliant device which uses human power instead of electricity. Another such device I’ve seen use a crank type device. These are great because they do not cost money for electricity or batteries, but also because since they use human power which when combined with the physical law that energy cannot be created or destroyed, just changed in it’s form, means that it is a productive way to burn off some fat.
There is one warning about the Forever Light however. Because they use powerful magnets to create the electricity for the batteries, they cannot be used while working in or around computers, televisions, or any other device that uses magnets itself. You could very well wipe or at least corrupt disks or distort screens. For these tasks, a more traditional form of light is required but for everything else, Forever Lights are marvelous.