The Lange 31 has, for nearly a decade, been the first and only mechanical wristwatch with a power reserve of 31 days and a patented constant-force escapement that continuously delivers uniform torque. Now, A Lange & Söhne has a new variation in white gold and a grey dial. It also features rhodium gold hands, a sapphire crystal caseback and a dark brown hand-stitched alligator leather strap. Limited to 100 watches.