Casio F91WS7EF is a classic, lightweight digital watch from Casio’s Collection series with a simple, everyday-wear design. It features an easy-to-read LCD display with an LED backlight for visibility in the dark, a 1/100-second stopwatch that measures up to 60 minutes, and a daily alarm with an hourly time signal. It also includes an automatic calendar showing the date, day, and month, plus a choice of 12- or 24-hour time formats. The watch is water resistant (splash/rain resistant), has a long battery life of about 7 years, and comes in a durable resin case and strap.Basic InformationCase size : 38.2 × 35.2 × 8.5 mmWeight : 21 gCase and bezel material : ResinBand : Resin BandWater resistance : Water ResistantPower supply and battery life : Approx. battery life: 7 years on CR2016Glass : Resin GlassCompatible band size : 145 to 200 mmWatch FeaturesStopwatch : 1/100-second stopwatch, Measuring capacity: 59'59.99''Measuring modes: Elapsed time, split time, 1st-2nd place timesAlarm/hourly time signal : Daily alarm, Hourly time signalLight : LED lightLight color : LED:GreenCalendar : Auto-calendar (set at 28 days for February)Accuracy : ±30 seconds per monthOther features12/24-hour formatRegular timekeeping:Hour, minute, second, pm, date, day