Tecnifibre X-One Biphase Tennis String is Tecnifibre’s premium string. It is designed to take playability and durability to a new level by providing ultimate performance of power and feel, while extending string life by 20% and offering increased spin. X-one Biphase joins together H2C (High Heat Capacity) and NRG microfilaments to acquire this high power and dynamic response. X-One benefits from a process (trimerization), which bonds polyurethane to protect against wear and notching while maintaining high comfort and feel.provides the highest level of power and control. The X-One Biphase string is the most efficient in this range on the criteria of playability, durability and integrity. The particularity of this range is to present a wear indicator, which allows the player to change the string before the complete breakage. This witness is manifested by the significant fraying of the rope at the place of the impact of the ball. A leading brand in strings, Tecnifibre has built its success on the design and production in France of the first multifilament strings. These strings are renowned and appreciated for their power, their comfort and their strong ability to retain their qualities over time.