... lineStructureMaterial: Polyester upperSize: 17. 18Performance: Single Core Multi layer ,Outer protruding edges and corners, The line can not slip the ball bite,Small ... ,No traces,no need While playing, the ball struck side line; Strong tensile,Pounds is very small bac;Ribbed design,Increased ... racket shock;Durable and strong,More than any other ball line 4 times.