This is the best and safest way to secure your canoe(s) on the roof of a 4WD. You bolt the racks to the roof rack rails, load the boat, then slide the rack to fit what you're carrying, tighten the large wing nut, then secure with the included straps. I have used them on several cars with roof racks and they have worked great. However, I found that the bolts were too long for some of the factory roof bars (the bolts made contact with the roof) and I had to buy shorter bolts. They use a metric bolt, so keep that in mind if you need to buy shorter rack bolts. I've used them several times without a single incident. Well done - nice shelf!
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