Material: Self-fusing silicone rubber

To use the tape, simply stretch it around the material you are trying to repair. As you wrap the tape in a circular motion, it begins to seal and “fuse” itself to the material. The most common forms of self-fusing / self-amalgamating tapes are made of silicone rubber (though other types also exist). They are designed to create a strong, seamless, rubbery, waterproof, and electrically insulating layer.
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Self-amalgamating waterproof rubber repair tape
5. Test the Seal Once applied, check to see if the seal is tight. You can do this by attempting to slide a piece of paper between the door or window and the frame; if it doesn’t slide out easily, your installation was successful.