It's flexible

Solid core synthetic string

Wilson US Open Extra Duty 24 Cans are the gold standard for the top players in the world

Measures string size

This do-it-all organization system acts like your courtside valet

Tecnifibre X-One Biphase 17 1.24 660' Reel Color:Natural It's flexibleTecnifibre X One Biphase 17 is Tecnifibre's flagship playability tennis string, and for good reason. With plenty of technology packed in for maximum power, feel and comfort, this string is even a great choice if you suffer from arm pain. The 17 gauge is even thinner for increased feel on those touch shots. Biphase process offers 20% increased durability. Multifilament Synthetic string.