You literally need no tools to install this cargo box. It is bigger than any other I have seen on the road, yet it is stable riding on the roof. I don't plan on leaving it attached year round, only for travel and camping trips. The good news is that is as easy to take off as it was to install. It works for me.
3D Maxpider roof bag
We used this on a vacation this summer. I was surprised how much we were able to fit in it. With zippers on both sides, loading it was easy. The only complaint I would have is the bolts were too long. They actually rested ON my roof and would have damaged it significantly if I had left it. I have a Mazda CX5 and the Mazda roof rack/ cross rails which I think are lower than a lot of roof racks. When the bag was loaded it was even lower due to the weight. I bought 2 inch bolts.