The Shake Flashlight uses no batteries or bulbs. Instead it uses Faraday's Principle of Magnetic Induction and a super bright LED to produce light without batteries. The flashlight is shaken for a few seconds to recharge an internal capacitor and it will then provide upto an amazing 10 minutes of light. Shake it longer for up to 30 minutes of constant light. How does this happen? As the flashlight is shaken, a magnet passes through a metal coil which, when you shake, "induces" voltage in the coil generating electricity. During prolonged use it can be shaken for 10-15 seconds for every 2 to 3 minutes of super bright light. The light requires no maintenance so it can be left in your home or car for a longtime but will still be ready to produce light. The bright LED will last for thousands of hours and does not burn-out like a typical lightbulb - it should never need replacement. Great for home, car, camper, boat, or emergencies. Imagine exploring without the fear of ever running out of light. No need to worry about light if your car dies during a dark and stormy night. You'll be in great shape even if you have to signal for help in the pouring rain because it's 100% waterproof. The light it emits is twice as bright as an ordinary flashlight and is visible for up to one mile. This is a flashlight that never needs batteries, replacement parts or even bulbs for that matter. Now that's peace of mind.