Looks like there a few models. The DA40 are the ones I see the most.
Originally Posted by
Scooper
From its general appearance it looks like it might be a mid-seventies model similar, but not identical, to these. It doesn't look like the UNS 40 folds, and the DA 40 E doesn't have a rear derailleur or the same folding mechanism. I don't believe these and similar models are particularly rare.

Originally Posted by
Scooper
This 1980 PNSM 40 looks like it has the same rear derailleur and folding mechanism.
