bump
Well, I think they're for children, I suppose even quite young ones, as long as they understand anything read to them in books. (Maybe even if they don't understand it, it's still planting seeds of the Faith -- as good as any other story you might read to them)
As far as the maximum age, I'd say about 10 -- the books are clearly aimed at youngsters. It depends on the kid, of course.
God bless,
Matthew