The Lange 31 is the world’s first mechanical timepiece with a long power reserve of 744 hours or 31 days. It isn’t wound by a crown but by a key with a built-in torque sensor so it disengages once the watch is almost fully wound. The impressive 62-jewel hand-wound caliber L034.1 that powers this watch is encased in a 45.9mm case in solid 18K rose gold. The watch has a silver-toned dial with applied rose gold index hour markers, a large double date window at 10 o’clock, a small seconds sub-dial at 6, and a power reserve indicator at 3. The movement is visible from the transparent case back. This watch comes with a brown leather strap.Papers and the manufacturer’s box accompany this A. Lange & Shne Lange 31 Silver Dial 18K Rose Gold Watch 130.032F.