The X-ONE BIPHASE string is the best performing string in this range on the 3 criteria of playability, durability and integrity. The special feature of this range is the wear indicator, which 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. 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, their comfort and their strong capacity to preserve their qualities over time. Colour : natural Main material: Polyamide, polyurethane, silicone finish Recommended tension between 22 and 25 kg Maximum tension: 32 kg Not recommended for heavy string breakers (< 10 hours of play). String made in France. PU 400: 400% elasticity for great comfort and dynamic performance. Elastyl® fibres (50%): +12% elasticity compared to a standard PA. Provides enormous elasticity for maximum power. H²C Fibres (50%): Maximises performance with high temperature fibres for better tensile strength. Biphase Process: Exclusive "pre-stretch" process to provide better tensile strength and life. Visible and noticeable on the string, it increases the spin. Best seller worldwide The performance of the casing without the defects of the casing.