OK< this is a bit of an odd duck. The front end of the lens is pretty standard, APO Sironar N 150/5.6 with a Copal 0 shutter. The aperture is smooth, the shutter fires and the timing seems OK to my ears. The cosmetic looks good. The glass is very clean.
The back end element though, seems to for a smaller format than 4x5. May be for 35mm? I do have both front and rear caps.
If someone has a use of it, please make reasonable offer. Otherwise, it will just sit on the shelf.
Or if you have a suggestion what it can be used for, I'd appreciate it too.