Ulysse Nardin Berlin Split Second Chronograph

Back in the 90's, Ulysse Nardin produced a series of split second chronographs referred to as the Berlin Split Second Chronograph. I've owned three of these over the years and they came in a few different configurations.

While the watch was made in steel, steel/gold and all gold, the most curious thing to me was two different dials resulting in a Berlin 1 (small hour minute dial at 3:00) and a Berlin 2 (central hour/minute w/GMT at 3:00). Both housing a split second chronograph. It is unclear what changes to the movement are necessary to put the hour/minute hand in the center and add the GMT.

Both feature mother of pearl subdials for the chrono with 12 hour total measuring time. They are 40mm in diameter and approximately 14mm thick.

From one of the auction houses selling a Berlin 2:

the movement is noted as Cal. 13 UN-58 nickel-finished lever movement, 27 jewels, engine-turned silvered dial, applied baton numerals, outer five minute divisions and tachymetre scale, three mother-of-pearl subsidiary dials for 30 minutes and 12 hours registers, constant seconds, engine-turned subsidiary dial for 24 hour indication, large circular case, stepped lugs, back secured by five screws and inscribed Berlin 1907, screw down crown, three round chronograph buttons in the band, stainless steel Ulysse Nardin buckle, case, dial and movement signed

My first Berlin 1 was in SS with a blue strap. I sold it regrettably, and bought the two tone version a few years later...not my favorite combination.

Berlin 1, in SS and rose gold

The back shows an engraving of the medal of the city of Berlin, where in 1907 UN received an award at the Universal Exposition due to the precision of its chronometers. I couldn't figure this out for a long time until I looked at a post 10 years ago where Tim Jackson had the answer (power of the internet).

I next purchased a Berlin 2 on a bracelet, which was also an option. I will someday put it on a blue alligator with tang buckle. I think it will look better.

Berlin II in SS