A great conversation piece, the Accutron Gemini stainless steel men's watch (model 26A09) features a unique sub-skeleton window at 12 o'clock that offers a view into the sapphire crystals of the automatic watch movement. It also offers an applique accent of Accutron's signature tuning fork. This large-sized timepiece features a raised bezel that frames the black dial, which is accented by a patterned center, full Roman numeral display, and luminous hands (with seconds hand). It's completed by a stainless steel bracelet band featuring small, squarish links and a double push-button deployment buckle. Other features include an exhibition caseback, scratch-resistant sapphire crystal, and water resistance to 100 meters--suitable for recreational snorkeling and light recreational diving. An automatic (or self-winding) watch is fitted with a device (rotor) that automatically winds the spring by using the force of gravity. It needs no battery, but it will stop if you have been physically inactive for an extended period of time--as long as you're moving, the watch will stay powered. Swiss watchmaker Abraham-Louis Perrelet invented the self-winding mechanism in 1770. It worked on the same principle as a modern pedometer, and was designed to wind as the owner walked.