Once upon a time Stowa had a gentleman that modified the hand winding Unitas movements to center seconds and they sold the watch as the Flieger Original, it was a perfectly sized 41mm with 22mm lugs and about 12mm in thickness. The gentleman that did the modification died a few years ago and Stowa has not offered the FO since then.
They still sell a version of that watch but it no longer has a center seconds, it has a subdial at 6 or no seconds hand. The big Unitas movement fills up the sapphire crystal on the back of the watch and looks fantastic. The same movement is in the Marine Original.
The 40mm flieger Stowa currently sells has a 2824 automatic movement. A few years ago when ETA 2801 hand winding movements were available you could request your flieger be built with the 2801 for a 50 Eu premium. I had a Baumuster B built with the 2801 at this time. It is quite nice but the smaller 2801 does not look as impressive as the more substantial Unitas movement when looking at the back of the watch. I also have an A dial flieger with the 2824 Top movement. Although the A dial is 1mm thicker to accomodate the auto's rotor the watches wear the same and I enjoy both of them. I would prefer the larger 41mm case with the Unitas center seconds but since it is unavailable I am happy with my 40mm fliegers.
The watches are below. I do not have a photo of the 2824 from the backside but the Top movement is finished as nicely or perhaps even better than the 2801.
Baunuster B
The 2824 A dial
![](http://minutewheel.com/img/watches/stowa/stowa_0110.jpg)