Yeah what he said. They're plastic and only on the inside. They are there to help you site the corners easier when coming through elevation changes.
Here ya go, this'll give you some idea of what the track's like. I came down into the Intermediate group for a few sessions last weekend to get some video of a few friends.
23MB Quicktime movie around Beaverun. Umm, ignore that ending. That part of it is not what all trackdays are like. LOL.
