I've used this for quite some time, replacing the Prince Duraflex. It's a great string.
Although this string is very stretchy, it is very powerful, long lasting, and easy on the arm. I string it at 45 lbs, ala John McEnroe.
I bought these strings because of a good word from a friend of mine. They are very easy on the arm. I use the Prince O3 White racket and have a medium swing speed. With these strings, I serve effortlessly and when volleying, I have total control. The only thing that would make these strings better is if they lasted longer. I've had them for 2 weeks and play constantly and they're almost done. But, overall, I would certainly recommend these to any player.