Li-Ning's No.3 Boost string promises 'Extra Repulsion Power'. The core of the string is made using heat-resistant and high-intensity nano braided multifilament. While the outer part of the string is made using heat-resistant and high-intensity nylon, which ensures that tension is evenly spread throughout the racket. The compound resin coating provides the utmost care to the string and ensures elasticity for better performance. This 0.63mm string offers a high repulsion power and a comfortable hitting feel.