Monopusher, column wheel chronograph with both the seconds counter and the minutes counter acting from the center of the watch - resulting in an extremely easy to read elapsed-time indication.
As if the watch and movement were not interesting enough, this prototype was not made by Marco Lang (right), but his apprentice Johannes Jahnke (left). Johannes finishes his three year apprentiship with Marco in July.
I did not know who to who to congratulate first; Joahannes for his precocious skill in constructing such a beautifully finished and functional watch, or Marco for excellent mentorship.
While they make a great team, I hope we see a watch with Johannes Jahnke's name on it . . . accompanying with his own application to the AHCI.
For more information: http://www.lang-und-heyne.de/en/caliber4.html