>>3920585Yep, it's M39 rangefinder lense. I really appreciate Fuji's opportunity to mount almost every lense you can imagine.
It's cheap as hell (~10 bucks for a lense!), foldable (as I know, this feature will persist on Fuji via adapter) and provides good image. I used to have one, but bulked it (10 bucks is 10 bucks). Here's one frame I shot with it.