Got some PM and e-mail regarding the GUB 09-20.
I think the pictures already tells a lot. The 09-20 was produced from 1971 to 1990, app. 3.399.000 pieces have been made. Diaméter is 5 1/2'''lines.
It was originally designed to fit ladies watches ("Clipper") for example. Not easy to service because of the 3/4 plate.
Movement dimensions: 13x15,15 mm, height 3,5 mm
The movement was later mounted into smaller men`s watches.
A lot of those watches do pop up in larger quantities on ebay. I do not think those are a real bargain or a valuable collector`s item.
However the GUB 10-30 is.