The Diadem Elite XT™ 17 tennis string uses Star Core Technology that provides players with extreme bite on the ball. The unique six-pointed star shape of this co-polymer is engineered for maximum spin. This string is stiffer than the Solstice Power which gives the best in string tension maintenance and powerful response. High quality co-polymer. Unique, six-pointed star shaped to deliver ultimate spin. Ideal for advanced level players looking for spin and explosive response.