Thanks for all the kind words everyone. Some more info.....
Both watches are SS, and 35mm. Both are from 1936-1938. The white dial has no reference and the black dial is a 5160. Although there are many slight variations on these dials, neither one is in Sala (exactly).
@Severin the graphic you pointed out is as close as it gets in Sala, which is still not exact. Although at first glance these two look like identical twins, they are actually quite different. The sub dial size is very different. The white dial has railroad tracks around both subs, the black only on the left. The Compur font is different (and it's interesting to note the thicker Compur font on the black dial very often has the letter C slightly offset in the exact same way you see here). Both are base 1000 obviously, and I also find it amusing to see the combination of rounded 3 in the left subdial 30 and the flat 3 in the right dial 30, which in later dials can sometimes be a dead giveway for a redial (except on Aero's).
It's interesting to note the hands are almost exactly the same, down to the slightly thickened sword hands in the sub dials, but you will note also the stick hour hand is thicker on the black dial. All these amazing little consistencies and inconsistencies are part of the magic and madness of UG (and I assume other brands from the same period), using different sub contractors and different batches.
The white dial watch was purchased in Geneva by the original owner in the 30s when he lived there, and eventually came to me via his grand children. The black dial was also in Europe, and much harder to land. It was the kind of situation where something pops up, I bought it, and suddenly there were many competing offers trying to sabotage the deal. To the sellers credit, they were willing to honor the fact that I was the "first buyer", and we eventually settled on a much higher price, many many multiples of what I had already "bought" it for. As they said, they were not well off, and could not afford to turn down much higher offers, but also wanted to respect that I was first in line. So we eventually settled on something that we could both live with. It is interesting to navigate these financial and ethical waters, which happen quite often in the watch collecting world. Anyhow, it took a long time to sort everything out, but it's finally here.
It is almost impossible to photograph both dials together, as the white one is pearlescent and washes out very easily, and the black one needs a lot of light, but here is a modest attempt.......