Tecnifibre sent me a set of their new X-One Biphase, 17 guage, perhaps because I have used Tecnifibre for a while now. I have used Tecnifibre TRC 17 lately, in a hybrid with Forten Sweet 17 in the crosses, strung proportionally from 55 to 45 pounds in a Head Ix3 midplus. Since Tecnifibre touts this new string as the next coming of gut (don't they all?), they recommend prestretching it. I want to string it in a hybrid before the weekend, and try it. With a hybrid, if I don't like the tension, I have another chance. I was planning to just string it at a straight 55, given the recommendation to prestretch. I am 50 years old, am a 4.5 all-courter, with more af an emphasis on the baseline. I hit an Eastern forehand, with some topspin, and a one-handed slice and topspin backhand. A normal slice serve, with no kicker. If you have tried the string, and have any comments whatsoever, they would be most appreciated. Thanks in advance to anyone and everyone.