Once the windshield is in they just snug up to the bottom, the little tang(wing) thingmajig at the top tucks into the bright trim as its installed. I think its supposed to be some kind of 'flashing' material to divert water, but judging by most of the 2nd gens I have seen with a rotten cowell, I dont think they worked! I havent seen too many restos with these installed, I dont think a lot of people even know about them. Plus, like I mentioned when I bought mine a few years ago they were stupid expensive for what they were, but hey, its only money