Purchased on the advise of my physio. The principle is good. But it only comes with one set of finger cords which were far too tight for me. They restricted blood supply to my finger tips so that I could only use it for very short periods!
It's a nice tool for stretching your fingers and training those opposing muscles but I can't see it lasting forever. The rubber band seems fairly flimsy so not great value for money. I am happy with it for now.
I got this for a mate to happy him with he's physio and he love's it.