For the ultimate in spin, Tourna Big Hitter Black 7 17 brings bite to a new level. This German-engineered copolyester string is designed for medium power and impressive spin. During the manufacturing process, this string is extruded through a special dye to create a sharp, seven sided string designed to grip and rip the ball. To improve playability, Big Hitter Black 7 was created with mid-range power, incredible precision, and comfort in mind. The co-polyester nature of the string allows it to remain durable while maintaining flexibility for a softer feel than traditional poly strings. Our testers were obviously most impressed with the spin generation of the string and the power level helped to keep balls deep with greater spin to dictate play from the baseline.