6 elements in 4 groups, put together in a small and neat package covering 36x24.
However, aside from portability and/or being collectible, I don't really see the point of it.
It's neither 1:1, nor very fast. It would be a good lens for a walk during the day, but so is almost any other.
edit/add:
All the other lenses from SL-II line have very clear and distinguished places and ideas. A normal pancake, a wide pancake, a normal/short telephoto fast lens.
However this one doesn't really seem to be well suited against any particular task or shooting style.