These low profile mounts allow you to chop down the rails on your SCX10 II XJ roof rack for a cleaner look.
Because of the shape, they also help prevent your roof rack from catching on everything the trail has to offer.
Installation does requires you to permanently modify your stock roof rack.
Installation Instructions:
http://www.lockeduprc.net/instructions/scx10iilowprofileroofrack/scx10iixjlowprofileroofrack.pdf
You will need 2 parts for a full installation