This calculator uses "Faraday?s Principle of Electromagnetic Energy" to operate. A magnet moving by a copper wire produces an electric current that powers the calculator ? no batteries required! Shake it left to right non-stop 20-25 times, and enough electricity is generated to operate the calculator for 10 minutes. When the digits on the LCD screen dim, just shake it a few more times to recharge - your calculations won't be lost. Available with silver aluminum face plate, ergonomic rubber grip and keys, and a large transparent display window for viewing the charging mechanism. Calculators provide an interactive experience. Gift boxed.