A. Lange & Sohne 221.025 1815 Up & Down, 221025, platinum on a strap with a platinum tang buckle, manual wind caliber caliber L942.1, 45 hour power reserve with indicator at 9 o'clock, silver dial with painted Arabic numerals, blue steel hands, sapphire crystal, display back, size: 36mm, thickness: 8mm, Like New with European Watch Co Box and Warranty Card. This is platinum A. Lange & Sohne 1815 Up & Down, 221.025. It has a black leather strap with a white gold deployant buckle, and a scratch resistant sapphire crystal. It includes an exhibition sapphire display case back secured by 6 screws. The 36mm diameter solid three-body case, rounded bezel, and downturned lugs are polished. The dial is silver with black painted Arabic hour numerals, rare blued steel alpha hands, and an outer railway minute track. There is a subsidiary small seconds dial at the 4 o'clock position, and a 45-hour up-and-do wn power reserve dial at 8 o'clock. It's water resistant to 25 meters/80 feet, and the 8mm thick case, dial, and movement are all signed. The mechanical manual winding A. Lange & Sohne Caliber L942.1 is Glashutte three-quarter plate, and rhodium plated with fausses cotes embellishment. It's constructed with 27 jewels, 6 screw-mounted gold chatons, a glucydur screw balance, and a shock absorber mechanism. It includes a Nivarox spring with gooseneck fine adjustment, a beat adjustment via a regulating screw, and a straight-line lever escapement. It has a self-compensating flat balance spring, a monometallic balance that's adjusted to 5 positions, and bridges with Glashutte ribbing. The rotor oscillates at a frequency of 21,600 vph (3 Hz). The 1815 collection refers to the birth year of company founder Ferdinand A. Lange. Their up & down power-reserve indicator was originally utilized in historic pocket watches and marine chronometers, dating back to a Lange patent granted in 1879.