The new Eco-Drive Perpetual Calendar with Twin Date, the Calibre 3100, utilizes three independent motors to operate the hands and date display, allowing each of the two number discs to move separately in the oversized display window. Perpetual Calendar Twin Date Display Non-Reflective Mineral Glass Crystal 12/24 Hour Time Screw-In Case Back Water Resistant to 100 Meters 180 Day Power Reserve Strap features a Push Button Deployment Buckle 40mm Case Width not including crown