25% reduced speed for greater control! Premium high visibility felt for exceptional durability Green ball for standard 78' tennis court Meets all specs for USTA "10 under" tennis and ITF "tennis 10S" programs Similar in performance to other suppliers Quick Start 78 balls Features 25% reduced speed for greater control. Premium high visibility felt for exceptional durability. Green ball for standard 78' tennis court. Meets all specs for USTA "10 under" tennis and ITF "tennis 10S" programs. Similar in performance to other suppliers Quick Start 78 balls. Balls are standard size and pressureless.