The sporty silver-tone Citizen Eco-Drive 180 Titanium men's watch is rugged enough for sailing and snorkeling, and stylish enough for the office. The large, round watch case (measuring 1.5 inches wide) and bracelet band are both made from solid titanium, which is nearly 50 percent lighter than steel, but 30 percent stronger. It's also particularly resistant to salt water corrosion, as well as hypo-allergenic--perfect for those with metal allergies.

It features an engraved elapsed time unidirectional bezel that frames a silvery gray dial with luminous hands (with red-tipped seconds hand) and dial markers for easy visibility at night or while under water. The smooth bracelet band tapers slightly from the watch case, and balances brushed and polished finishes. Other features include a magnified date function at 3 o'clock, a push-button safety clasp, scratch resistant mineral crystal with anti-reflective coating, and water resistance to 100 meters (330 feet).

This watch is powered by Citizen's unique Eco-Drive, which absorbs sunlight and any artificial light through the crystal and dial to recharge the watch continuously. With regular exposure to light, the Eco-Drive continuously recharges itself for a lifetime of use. This watch's Eco-Drive provides a 178-day power reserve, and it can be recharged with just 2 hours of exposure to light.

Citizen Eco-Drive series watches are powered by energy derived from a number of light sources. Let's look at the mechanism that makes this possible. The energy that powers the watch is produced by a solar cell. This amorphous silicon solar cell directly converts light energy into electrical energy. Making replacing batteries an act of the past, the eco-drive is a timepiece that converts the infinite source of light into driving energy. Not using batteries of a disposable type, this timepiece neither reduces the limited resources on earth nor causes pollution either. It is easy on nature. The rechargeable battery does not incorporate any harmful metals like mercury, lead, and cadmium. Besides, harmful products such as Freon are not used for the production of the product and materials. That is because this watch has been crafted in consideration to the earth. Eco-Drive is the generic name of Citizen watches that run on light-generated electricity

Watch Information Model number: BM6150-56A Crystal material: mineral Clasp: safety-fold-over-clasp-with-push-button Case material: titanium Case diameter: 42.00 millimeters Band material: titanium Band length: mens-standard Dial color: black Bezel material: titanium Movement: analog-quartz Calendar: date Water resistant depth: 330 feet

1. The amorphous silicon solar cell is a structure incorporating amorphous silicon thin film which is deposited on a variety of substrates including stainless steel, glass, and plastic sheet. 2. This amorphous silicon film has a three-layered structure (so-called p-i-n structure), consisting of the p-layer doped with a small quantity of boron, an i-layer composed of only amorphous silicon and a n-layer doped with a small quantity of phosphorus. In the i-layer, the thickest of the three, the energy conversion from light to electricity is performed by absorbed light (photons). 3. When the incident light is absorbed in the i-layer of the solar cell, the valence electrons in the i-layer get excited at a certain probability to the conduction band (to be conduction electrons which carry negative charges) and simultaneously holes (vacancies in the valence band, which carry positive charges) are created in the valence band. 4. Because of p-i-n junction, a built-in potential exits in the i-layer. This built-in potential pulls conduction electrons and holes towards the n-layer and p-layer, respectively. 5. Consequently, the p-layer has excess positive charges, while the n-layer has excess negative charges. Connecting two layers by a conductive wire, a photo-current flows from p- to n-layer. Light energy from the sun or lamps Creation of electron-hole pairs in the i-layer of the solar cell Separation of electrons and holes as a result of the built-in potential Photo-current flows when connecting p- and n-layers by a conductive wire