It's hard to believe but it's true. No batteries or bulbs to replace, ever. Your energy powers the flashlight so you can have light any time, any where, for as long as you need it. Just shake the flashlight back and forth for 30 seconds to recharge the internal battery and generate more than 20 minutes of light. White LED bulb is 70-80% efficient and rated for 100,000 hours. Electricity is generated by a strong magnet sweeping back and forth through a coil when shaken. Durable plastic housing is shock resistant, waterproof, will never corrode and it will float. The perfect emergency flashlight! 10"L, less then 1 lb. Imported.