I believe they add about 6-8" to each wing. If you need more accurate info, someone else may have exact measurements.
I have them on my SS7, but if I were doing it again I would go with the standard tips. They definitely add more wing area, which I think is unnecessary. My kitfox seems to float longer and has a somewhat flatter landing approach than friends I fly with who have standard tips on their SS7's. They are supposed be more efficient in handling the wingtip vortices, but I don't notice any measurable difference. Others may have different opinions. They also make it more difficult to install wingtip nav and landing lights.