The Pioneer Mk I is a replica of the first precision chronograph made by Hanhart in 1938. With this unusual single pusher, all chronograph functions - start, stop and zero setting - are performed by a single pusher and always run in strict sequence. Unlike its two-pusher counterpart, the chronograph second hand cannot be kept running after it has been stopped; the next time it is pressed, it inevitably jumps back to its starting point. For this reason, the caliber used for the Mk I had to be slightly redesigned. The lever, which is located directly below the pusher that is normally positioned at 4 o'clock, has no function. The third stroke on the chronograph cam is thus performed by the large gearshift. For this purpose, this cam is modified at Hanhart so that an additional prong runs along its lowest level. This allows the gearshift to control not two, but three positions