Ordinary dry cargo containers only have one container sealing strip. The main function of the door strip is to prevent water leakage. For insulated containers, another inner seal needs to be added. Its main function is to serve as the last line of defense to limit the amount of oil leakage. In fact, the two are complementary to each other. Common cross-sectional forms include c-type, j-type, cj-mixed type, and composite combination type, etc. The latter is mainly used for insulated containers.