Alright, here goes:
With and without the phone attached. The lens is mounted on a tray sliding on a guiding rail (see arrows in first pic), then there's a thumb screw to tighten it in place (clearly visible in both pics). The mount has springs inside that allow it to stretch and grab a phone even larger than N5.
The lens hole is exactly the size of the black ring around N5 lens, but even if that had been much smaller, it'd be ok as the lens on the phone is much smaller than the surrounding black ring.
Best way to attach it is first fit the mount to see that the lens hole is lined up, and then screw in the lens.
Let me know if there are any more questions.
By the way, I dropped the lens yesterday on a stone floor from about 5ft, it left a small mark on the body but everything else is undamaged - nice to know, eh?