Thanks for that info. I wonder if your spool has the three holes on the end opposite the keyslot, though, or is just a plain metal spool like a longer 122.

I unspooled it today. Tried to load it into a Seneca Box Scout 3A (which is in actuality a 3B, but we won't mention that) and the film stock disintegrated, which isn't surprising given its age. I did notice that it's narrower than the paper at one end: looks like they loaded 122 stock into a slightly wider paper backing. No idea why they felt it necessary to do this: why not just build the camera to use 122 in the first place, and save having to make one more film size.