The legendary chronograph caliber Buren 12 with a cam switch is a joint development of Hamilton-Buren, Breitling and Heuer and consists of a mounted chronograph module by Dubois-Depraz 8510 on the original Buren 1281.
The Buren 12 beats with 21.600 A/h, the Buren 11 with 19.800 A/h. Junghans used the faster Buren 12.