Hey Wade, thanks for asking! This gear bag can either mount right onto your car roof (touching the car - but with a protective padded nylon layer to help protect the roof) OR it can be put on a gear basket. You can read more about that in the instructions which I've linked below. As for the weather resistance, they suggest encasing anything that must remain 100% dry inside a waterproof bag before loading it into this storage bag, and to keep the zipper flaps down and flat during travel to avoid water sneaking in through the zippers. Dry sacks, big zip lock bags, or something along those lines should do the trick.
Date published: 2017-02-18