Kryos MechaQuartz Chronograph, Cal. 631

JLC Caliber 631 (IWC Caliber 631)
This is a hybrid movement. It combines a mechanical chronograph movements with a quartz controlled step motor. It consists of 222 parts, is able to measure 1/4th seconds and my favorite feature while traveling. If you change the time zone, just start the chronograph, then change the time - hacking the time will not stop the chronograph second - and after finish setting the new time zone, simply synchronize the seconds. I am traveling quite a bit and I really love to have the possibility to keep the seconds as I had set them before the trip.
And by the way, the dirt on the case is about 12 years old. I bought this watch ca. 1991 and had never opened it. No sign of corrosion, just the normal dirt that will of course accumulate on the outside frame under a case back. And as you can see, the gasket ring did not let anything into the movement, it still looks brand new.

Please click here to see an example of the same Caliber 631 used by IWC

Please click here to seen example of the Caliber 633 used by IWC, basically the same movement but with an alarm function