Calibre 3100 Twin Date Collection. Perpetual Calendar Automatically Adjusts for Odd and Even Months and Leap Years through 2100. Eco-Drive Technology - Charges in Sunlight or Indoors - No Batteries to Change. Blue Dial with silver tone hands and markers. Luminous hands and markers. Solid Stainless Steel Case and Bracelet. Push-button Deployment Clasp. 12/24 Hour Time. Large Date display. Low Charge Indicator & Time Reset Advisory in the Event it Ever Needs Charging. Screw-Back Case. Non-reflective scratch-resistant mineral crystal. Water resistant to 100m. Case measures 41mm wide by 11mm thick.