Made of optimal hollow-out silicon rubber. Being super durable, high tensile strength, UV & weatherproof, corrosion & wear resistance
Just stretch and narrow it down a little bit the seal to insert it into the gap.
an additional squeegee can be used to push the seal into the gap.
If you find it ends up way too long, somewhere must be stretched way too much in somewhere. Just lose it a little bit and push it straight down in the gap.
15 minutes will be enough to finish the job.