Casio About this item Water Resistant, LED light Stopwatch, Daily alarm, Hourly time signal Calendar, 12/24-hour format Approx. battery life: 7 years on CR2016 Technical Details: Product Dimensions ‏ : ‎ 6 x 6 x 4 inches; 3.84 Ounces Item model number ‏ : ‎ F91W Department ‏ : ‎ Unisex Batteries...