About the String: Your weekend club games and weekly training sessions require a durable string; try HEAD sonic Pro. Made of a unique co-polymer polyester with a soft molecular construction, the string provides a perfect combination of touch, comfort, and power. The reel is 200m / 660 feet of string. Features: Ideal for pairing with your favorite HEAD racket for top level performance. A great tennis string for club to intermediate level players. About HEAD: Born out of engineering a better way to ski and play tennis, we have used the most modern techniques available to improve athletic equipment for decades. Now, we have turned that same vision and attention to detail to all racquet sports to bring you nothing but the best sports equipment & workout apparel available.