The X-ONE BIPHASE string is the best performing string in this range on the three criteria of playability, durability, and integrity. Key Features: Wear Indicator: Allows the player to change the string before it breaks completely. This indicator is manifested by the significant fraying of the string at the point of impact of the ball. Leading Brand: Tecnifibre is the leading brand in strings and 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, comfort, and strong capacity to preserve their qualities over time.