Drove 600 miles with a week's worth of camping gear plus two dogs and still had room to spare in the back seat. The box stayed completely dry through a full day of rain on the highway, which was my biggest worry.
Drove 600 miles to a campsite with two dogs and a trunk full of gear, and the SkyBox NX swallowed all the bulky stuff so the back seat stayed clear for the pups. The latching mechanism felt solid when I checked it at a rest stop, no rattling at highway speeds. Honestly made the whole trip less cramp