The Detroit watch has been our signature fashion & lifestyle time piece for many years and it's clearly obvious as to why. Now it comes in a fully automatic version that uses a 21 jeweled automatic movement that keeps precision time and never requires a battery. With the natural movements of your arm this watch will keep ticking up to 48 hours even when not in use. The 50mm Detroit - Automatic is constructed of high grade 316L stainless steel to help resist any rust or corrosion from being in any marine environment. Water resistant up to 100 meters (330 feet) and is backed with a 5 year limited warranty (also available in a 44mm case size).