The Rolex Datejust 31 is a mid-size luxury timepiece positioned between the smaller 28mm Lady-Datejust and the classic 36mm model. It is celebrated for its balanced proportions, offering an elegant wrist presence suitable for daily wear and formal occasions.Key SpecificationsCase Size & Water Resistance: 31mm Oyster case, monobloc middle case with screw-down case back and Twinlock winding crown. Waterproof to 100 meters (330 feet).Movement: Powered by the in-house Calibre 2236 self-winding mechanical movement. Features a patented Syloxi silicon hairspring, Paraflex shock absorbers, and a power reserve of approximately 55 hours.Precision: Superlative Chronometer certified with an accuracy of $-2/+2$ seconds per day.Crystal: Scratch-resistant sapphire with a Cyclops magnifying lens over the date window at 3 o'clock.