(1) Appearance, the ball surface must be fine and not reflective, ball waist seam clean.
(2) bouncing height, the ping-pong dropped from 305mm height to the standard steel plate, bounce height between 240mm to 260mm, many experiments, if the ball bounces high or low for the first time, then the elasticity of the ball Inhomogeneous.
(3) roundness and center of gravity, the ball on a smooth, flat surface rotation, to observe whether there is a violent shock, then the poor stability of the ball, hitting the ball is not easy to control.
(4) hardness, with the thumb and index finger pinch the top of the ball, observe both sides of the same hardware and software. If the same degree of rebound, then the ball better quality, good performance.