There's a thread about these here.

I dug it out to do some photos for the thread and decided I could offer it also as I've never made a photo with it.

Lovely image on the GG. Crisp but not different from a RR as I can tell on a GG.

The original US Patent is here.

This one is mounted in a Working Optimo shutter. Easily seperated but the shutter is a nice addition from the 1920's. $345 + shipping