Introducing the Tecnifibre Triax 17 1.28 660' Reel: the first multifilament tennis string with co-polyester fibers. Stay comfortable after every swing from the PU HD covering that provides 15% more shock absorption than ordinary monofilaments. Increase spin and control on the court from the co-polyester fibers, which deliver 15% more firmness than standard monofilaments. The exclusive use of T.P.I. co-poly fibers adds durability so you can play longer. For a string that perfectly mixes spin, control, and comfort, choose the Tecnifibre Triax 17 1.28 660" Reel! Spin and Control: Co-Polyester fibers deliver 15% more firmness versus a classic monofilament. Arm-Friendly Comfort: The unique setting of PU HD adds 15% more shock absorption than standard monofilaments. Durability: Exclusive use of T.P.I. Co-polyester fibers increases durability by 50% so you can play longer.