The Tecnifibre X-Code HD tennis string set offers 100% polyester multifilaments & gives you the feeling of monofilament polyester without the shock & fatigue. It features the PU HD technology to ensure a firm feeling & good control & has an anti abrasion coating for added durability. The X-Code HD is the official string of the ATP World Tour & perfect to re-string one racket. This 12m (39.5ft) set is designed for power & precision.