This is a 950 Platinum A. Lange & Sohne Langematik Perpetual Calendar 310.025. It has an alligator leather strap with a Platinum tang buckle, and a scratch resistant sapphire crystal. It has an exhibition screw-down display sapphire case back secured with 6 screws, and correctors on the band. The 38.5mm diameter solid three-body case, rounded bezel, and downturned lugs are polished/brushed. This watch has a "Zero Reset" that resets the seconds hand to zero when you pull out the crown to adjust the time, making it extremely easy to precisely synchronize the watch. The dial is Solid silver with applied radial rose gold Roman numeral hour markers, luminescent rose gold alpha hands, and an outer railway-style minute track. There is a subsidiary dial for the day of the week that's combined with the 24-hours and day/night indication at the 9 o'clock position, and a constant small seconds sub dial combined with the moon phase at 6 o'clock. The sub dial at 3 o'clock registers the months and leap year. A large double-digit date aperture window is at 12 o'clock. It's water resistant to 30 meters/100 feet, and it has a power reserve of 46 hours at full wind. The 11mm thick case, dial, and movement are all signed. The mechanical automatic self-winding A. Lange & Sohne caliber L922.1 "Sax-O-Mat" movement is Glashütte 3/4 plate in German silver, with fausses cotes embellishment. It has a shock absorber mechanism, and it's constructed with 43 jewels, a straight-line lever escapement, and a monometallic balance that's adjusted to temperatures and 5 positions. It includes a self-compensating flat balance spring, a swan neck micrometer regulator, a 21K gold bi-directional microrotor with platinum segment, and a hand-engraved balance bridge. The rotor oscillates at a frequency of 21,600 vph (3 Hz). You can correct the date correction either by pressing one button to change all features collectively, or each complication can be corrected independently using recessed corrector buttons. Production of this reference started in 2001.