These Dunlop® Tennis Balls are great for beginners who want to develop skills. With an internal pressure 25% lower than a standard tennis ball, developing players can hit harder shots while still controlling the tennis ball. ITF Approved Stage 1AgeSuitability: 9-10 and beginners of all ages.Designed as a transition ball from Stage 2 to standard tennis balls.Size: Standard.Approx. 25% slower than a standard tennis ball.