Now the tricky part. Or, maybe the exciting part, depending on personal proclivities in the realm of manually wound chronographs. The base caliber here, on which Vacheron has put its perpetual mechanism, is the latest iteration of the well known Lemania 27-70. This is, of course, the legendary manually wound chronogrpah on which Omega’s lunar-bound 321 was based, in addition to the calibers found in Patek Philippe’s 3970, 5020, 5004, and yes, 5970. It’s also the same base that you’ll find in the lovely Cornes de Vaches from VC itself. But noted by Vacheron publicity this new 5000T reference features the caliber 1142 (not 1141) which means its ever so slightly thinner and now beats at 3 hertz instead of 2.5 hertz. That is a good thing, or so we’re told, but the truth of the matter is the change in the caliber came from Breguet (now owner of all Lemania IP) and for some time, Swatch was selling the 2.5Hz version of the caliber to outside parties while they would use the 3Hz version in Breguet products. Ultimately, we’re told via a friend of the Swatch group, that it was simply too costly to continue to produce two version of the same caliber so they began selling the 3Hz version of the Breguet 2320/533.1 (née Lemania 27-10) to outside parties, most notably Vacheron Constantin.