Combination quartz and tide clock movement which averages the Atlantic lunar tide cycle. The tide sector is calibrated for the east coast of the United States. Uses a AA battery. (Note: The clock will work for other tidal bodies of water but will need to be re-set more frequently.) * Maintenance-free, ultra-hard finish guaranteed to NEVER tarnish * Patented Slide-n-Lock™ Mounting System, no visible mounting screws, easy removal for adjustments & battery replacement * Weatherproof construction for outdoor use * Beveled glass crystal * Includes AA Battery * United States Patent #7,293,456 * Lifetime warranty on finish and movement * Dimensions: Dial: 4 7/8” (125 mm) Base: 6” (152 mm) Depth: 1 5/8” (41 mm) * Weight: 1.3 lbs (589 g) About Weems & Plath Founded in 1928, Weems & Plath is a company steeped in the rich tradition of navigation. They offer a wide spectrum of precision instruments ranging from brass nautical clocks and barometers to binoculars and children"s books. The company"s dedication to providing the highest quality possible is evident in every step of the building process. From development to production, Weems & Plath strives to be meticulous and offer exceptional service. The rich history and high standards of Weems & Plath will carry on into the future. * Quartz and tide clock * Tide clock calibrated for the east coast of the U.S. (can be easily re-set) * Tarnish-proof, waterproof, and maintenance-free design * Slide-n-Lock mounting system with no visible screws * 125mm dial diameter