The key to the quality practice of door and window seals lies in the sealing strips. The sealing quality plays an insignificant role. The materials of door and window sealing strips used in the market are generally PVC modified. The key role in soft PVC is nothing more than the quality of the plasticizers involved. The currently stable plasticizer is diphosphoric acid. Spicy fat, dibutyl fat. However, the current market price is very high, and some unscrupulous vendors use some other low-cost alternatives (waste engine oil, oil bottoms left in refineries, etc.), which poses a great hidden danger to the vast number of consumers.