Irvin, I need you help. I have some self proclaimed string expert telling me that Genesis Black Magic 17g is much much stiffer then Luxilon Timo, Ace and Black Widow. He also claims the local tennis shop agrees with this and recommended he use Black Widow. This shop recommends black widow quite often since it breaks frequently giving them more business. Anyway Black Magic was rated 5th out of all strings rated by Stringers Association and the only poly rated in the top ten.