The Penn QST 60 Orange Training Tennis Balls are ideal for advanced beginning players ages 9 and 10 playing on a 60’ tennis court. The QST 60 features a low compression core allowing greater control for longer rallies. Features:Low compression core for greater controlHigh visibility orange and yellow feltUSTA and ITF approved and endorsed by the PTROrange Ball for standard 60? tennis court sizeRecommended for advanced beginners, ages 9 and 10Specifications:72 Balls with 12 balls per bag; 6 bags per caseThe Penn QST 60 Orange Training Tennis Ball is also enjoyable for adults who require a slower playing tennis ball.