With A. Lange & Söhne Guarantee dated 21 August 2006 inside a Guarantee & Service booklet entitled Das Buch zur Uhr - The History of your Watch, instructions and polishing cloth.
Until the launch of A. Lange & Söhne's "Double Split", the French term "rattrapante" described the ability of a split seconds chronograph's superposed seconds hand to "catch up" with the main sweep seconds hand. Comparative time measurements were limited to 60 seconds, and could not always be used in an appropriate way.
Lange's "Double Split", the world's first flyback chronograph wristwatch with a double rattrapante mechanism, opens up a new dimension in mechanical time measurement. Beyond the ordinary stopwatch functions of a conventional chronograph, it can also handle lap-time measurements, time comparisons, and fastest/slowest lap measurements. Its additional flyback minute counter makes it possible for the first time to use these rattrapante functions in a truly meaningful way, namely for events that last up to 30 minutes - as opposed to conventional rattrapante mechanisms that could only measure times of up to 60 seconds
The newly developed Lange L001.1 movement is composed of 465 hand-finished parts, its balance beats at a frequency of 21,600 semi-oscillations per hour, allowing measurements to an accuracy of one-sixth of a second. Moreover, error-free readings are assured by the precisely jumping chrono minute counter and the precisely jumping rattrapante minute counter. During an on-going time measurement, the flyback function will immediately stop and reset the chronograph hands (and, with them, the rattrapante hands if they are still running) with only one press of a button. A new measurement begins instantaneously when the button is released again. This skips the otherwise necessary "stop" and "reset" steps.