The Datograph houses the Lange in-house flyback chronograph caliber L951.1 – a movement that was part of a changing landscape in terms of how enthusiasts, collectors, and the industry think about chronographs. Before its debut, little had occurred in the way of development of classic high-end chronograph movements for many years. We take it for granted that “high horology” is synonymous with “in-house,” but historically, it’s not true. Patek Philippe’s first in-house chronograph movement, for example, the CH R 27-525 PS, was only introduced in 2005. There were developments in more widely produced calibers like the Valjoux/ETA 7750, which came out in 1973, and there were, of course, the first automatic chronograph calibers of any kind, in 1969. We should also remember the F. Piguet ultra-thin chronograph calibers, 1180 and 1185, which came out in 1987. But mainly, high-end manufacturers relied on supplied calibers from chronograph specialists like Lemania. The Royal Oak Offshore is one example of this and illustrates the standard practice during the 1980s and 1990s, and even before. From launch, it used a movement based on the Jaeger-LeCoultre caliber 889 with a Dubois-Depraz chronograph module.