I purchased a roll from my local dealership and replaced all the trim on my previous TT when it began cracking and breaking because it got so brittle. I think I paid something like, $12 for a 100 foot roll. I took a piece of the old trim that wasn't cracked to my dealership parts store and they matched it, off the shelf. I replaced everything on the camper and still have, probably 50 feet left. It's white, but the trim on my current camper is all black now.
When you begin to insert the trip, start with one side and lay it in the track about a foot long. Then pinch the trim and insert the very end into the other side of the track. Once started, you can just pinch in the middle and slide right down the track. Cut to length only after you've inserted it.
The biggest problem I had was the tail dangling, and it wanted to uncoil all twisted. Then, I did it it 5-6 foot sections over the gutters area and would have to move the ladder again. So the roll was laid on the roof so it wouldn't pull out what I just inserted. It was easy, but a bit frustrating until you get the hang of it. After I caught on how to do it, the rest went very fast.
As stated above, don't stretch it. That's why pinching in the middle and just letting it self insert works so well. After it was inserted, I waited about 10 minutes before I cut to length at the ends, and then I left the ends about 6 inches longer to allow for some shrinkage after the immediate install. After a few more minutes, I trim back the 6 inches, leaving and extra inch and tuck it under. The little end caps screwed on top of the fold.
Good luck, and have fun. It's an easy job, just a bit tiring working from a ladder for almost everything so long.
