Thanks Mike - helpful and knowledgeable; as always.
I am dropping off an exposed roll of 120 today so I will for sure pick up a few more.
It looks like this, but says B-2 on the strap and inside. The shutter is, as you probably know, is done by a flick of the wrist and a snap of a spring! It looks like it may be a light-leaker, too. I have some very thin foam strips for sealing rangefinders, maybe it will work on the back door of this camera.
It also has little wings that fold in to allow the taking of half-frame pictures. A techno-marvel of the 30's!