Table tennis rackets are composed of three parts: the blade, rubber, and sponge. The rational combination of these three components determines the quality of a racket. We often mention terms related to table tennis rackets and sponges, such as "speed," "control," "resiliency," and "the hardness of the blade." In reality, these indicators do not have unified numerical values in the industry; they are simply categorized by various manufacturers to provide consumers with a reference during purchase.