The AAA grade pool cue balls made from polyester resin which provides exceptional scratch and impact resistance, and are precision engineered, ensuring superior playability and durability, measuring 2.25"(57mm +/- 0.15mm) in diameter and weighing 6oz(168 +/- 3grams). The balls can help you learn how to strike the ball in the same spot, and you can know more clearly which point will rotate it, as well as the angle and direction of rotation by observing the impact point. It is great for game rooms, bars, sports matches, leisure exercise, and players at all skill levels.