If the part you are talking about is the window channel lined with mohair (some call it felt), example:
https://www.steelerubber.com/flexible-run-channel-70-1108-57
You use these:
https://www.steelerubber.com/run-channel-clip-60-0374-58

Also, wherever you purchased from, give them a call and ask.

"Adding CFM to a truck will only help at engine speeds you don't want to use."
"I found there was nothing to gain beyond 400 CFM."