features a round case made of platinum or gold. The Datograph has a 39m case with an easy to read dial with the second and hour sub dials and the over size date window and a flyback chrono function. The Datograph Perpetual is one of the finest perpetual calendar watches available today and is available only in platinum. The A. Lange & Sohne Double Split chronograph features a double rattrapante feature and a power reserve indicator.