When rubber products are molded, they can’t be eliminated due to the cohesive force possessed by the elastomer after being pressed by high pressure. When they are molded and released from the mold, they tend to produce extremely unstable shrinkage (the shrinkage rate of rubber varies depending on the type of rubber). After a period of time, it can be calm and stable. Therefore, when a rubber product is designed at the beginning, regardless of the formula or mold, it is necessary to carefully calculate the fit. If not, the product size is likely to be unstable and the product quality is low.