Ecologically friendly, light powered Eco-Drive Caliber B877 Japanese-quartz movement; Charges in natural sunlight or indoor light Max power reserve: 180 days; Low charge warning: 3 days; Quick start ability; Charge time from stop state to max charge: Incandescent Light - 53 hrs, Outdoors, Cloudy (10,000 Lux) - 17 hrs, Outdoors, Sunny (100,000 Lux) - 6 hrs Durable, hardened non-reflective mineral crystal; Performs flight calculations with Pilot's slide rule inner bezel ring operated by crown at 8 o'clock Large luminous hands and hour/minute markers for easy readability; Dual-time function; Date feature at 3 o'clock Water-resistant to 660 feet (200 M)