If u look here u can see the trim thing:
http://rcdb.com/ig247.htm?picture=2
It's the dark strip between the 2 rails and runs down all but the top of the spiral. U can also see the block brake half way down which is why it can run 2 cars at once, scarily closely.
I've seen them many times at fairs here and once I read a review where the guy said with some of them where there wasnt padding on the roof taller paoples heads got bashed on the roof in the bunny hops.