IWC has been transitioning to in-house movements since 2000, enhancing the reputation and technical features of their watches. Part of this development includes the production of specialty high-end movements. The Cal. 94000 family is the basis for many of these since its launch in 2011. It uses two mainspring barrels, providing power for complications including a tourbillon and specialty digital time display. This was a departure for the company, which had previously relied on a single barrel design for long power reserve movements but suffered poor isochronism as a result.
Cal. 94900 debuted in 2012 powering the IWC Portugieser Sidérale Scafusia 5041. The two mainspring barrels are coupled, with a constant force mechanism integrated into the tourbillon to ensure stability of amplitude. The watch also features a perpetual calendar mechanism with a sidereal time display on the reverse.
The tourbillon is located at 9 00 on the dial and provides the running seconds display. A subdial at 12 00 on the dial shows sidereal time with its own hour and minute hand. A 96 hour retrograde power reserve indicator is at 4 30. The reverse side shows perpetual calendar date with day of year and leap year indicator. It includes a detailed celestial chart with the horizon, sunrise and sunset time, ecliptic, and celestial equator.