These horns carry the stamp of another famous Adler brother.
Like his brother Franz Oscar Adler, Robert Oswald continued the family business of building musical instruments.
In none of the literature I have come across did I find references to Robert Oswald Adler making saxophones however.
Therefore, one is left to wonder if he ordered stencils from other companies.
We do know that at least some of the ROA horns were stencilled by other companies, since I have found this example made by F.X. Hüller.
If he did make saxophones in his own factory, looking through the horns in this ROA gallery you see an evolution of styles and features.

Atlantic
Atlantic
It took a long time to find out that ROA made the Atlantic models. Enjoy the pics.

I've heard of and seen a horn called a "Buescher Atlantic." There were some Germanic horns with the Buescher name, but obviously not made by the Buescher company in the US.
ROA
ROA