Because the medium ball is 2.5 inches in diameter, the launcher will also suit ordinary tennis balls! The Classic Launcher comes with one Chuckit! The official diameter is 6.54-6.86 cm (2.57–2.70 inches) according to the International Tennis Federation (ITF). Balls must have a mass of 56.0–59.4 g (1.98–2.10 ounces). The large ball is 7.62 inches in diameter and the heavy ball is 9.5 inches in diameter. So these are for special needs only. There are two ways to launch a tennis ball using a Chuckit: stand back about 30 feet (9.1 m) from the ball and press the fire button or walk towards the ball at low speed (about 10 mph or 16 km/h) and release it. Both methods work well but you need to be sure that you have enough time before it hits the ground. If you don't get the ball in time, it will go over your head. You can improve your game by practicing different shots with the Chuckit. It's fun!