17 cubic feet. That's as much as many cars and small SUVs can hold, and you can relocate all the stuff you've been cramming into your car into the Thule Hyper XL Cargo Box. The Hyper XL includes intelligent features like an integrated light to help you see what's inside the box, aerodynamic design so your mileage won't tank, and dual sided opening to help with loading and unloading. It's easy to mount on your existing racks, or it'll certainly fit a new setup from Thule. If you're mounting it on a hatchback or sedan, you'll want to note the rear angled base, which allows for easier hatch and trunk opening.