A. LANGE & SÖHNE. A VERY FINE AND RARE PLATINUM WRISTWATCH WITH 31 DAY POWER RESERVE, REVOLUTIONARY KEY WINDING MECHANISM, DATE AND HACK FEATURE

The revolutionary Lange 31 is the first mechanical wristwatch with a power reserve of 31 days. The exceptionally high power reserve can assure high rate stability and consistent rate accuracy for an entire month. The watch features a key winding mechanism of historic pocket watches and can be wound with a stainless steel winding key through an aperture to the case back. This particular winding mechanism generates much more torque than would be possible with a crown. In order to prevent over tightening of the springs, this complex movement features a built-in torque limiting mechanism and a backstop ratchet that slows down the key when it is turned anti-clockwise.

The Lange 31 attests to the fine craftsmanship, technical excellence as well as aesthetic qualities at A. Lange & Söhne, making it a highly sought-after collector's watch.