Wilson Tennis on Twitter: "Stiffness: How much the racket frame flexes on contact Less Stiff=More Control More Stiff=More Power We measure Stiffness using the Stiffness Index (SI) Test. The more the racket
![Melbourne, Australia, 2015, May 9: String bed stiffness of a Tennis tour player frame is measured on strings. The measurement is used to check the qua Stock Photo - Alamy Melbourne, Australia, 2015, May 9: String bed stiffness of a Tennis tour player frame is measured on strings. The measurement is used to check the qua Stock Photo - Alamy](https://c8.alamy.com/comp/HWPC9N/melbourne-australia-2015-may-9-string-bed-stiffness-of-a-tennis-tour-HWPC9N.jpg)
Melbourne, Australia, 2015, May 9: String bed stiffness of a Tennis tour player frame is measured on strings. The measurement is used to check the qua Stock Photo - Alamy
![Amazon.com: S&S Worldwide Aluminum Tennis Racket. Mid-Sized 90 Square Inch Head. Modern I-Beam Aluminum Cross Section Design for Added Stiffness and Power. Adult Size, 27" L with 4-3/8" Grip. : Sports & Amazon.com: S&S Worldwide Aluminum Tennis Racket. Mid-Sized 90 Square Inch Head. Modern I-Beam Aluminum Cross Section Design for Added Stiffness and Power. Adult Size, 27" L with 4-3/8" Grip. : Sports &](https://m.media-amazon.com/images/I/61YygikJw1L.jpg)