In simple terms, during the manufacturing process, the different heat shrinkable tubes are heated to a standard high elastic state, and loads are applied to help the tubes expand. Rapid cooling must be performed while the heat shrink tube is still in the expanded state, and the heat shrink tube into the glass state. In this way, it can be fixed firmly. If the heat shrink tube is heated when it is used, or the heat energy is encountered, then the heat shrink tube will change back to a high elastic state.