WATERPROOF: This premium quality car top bag is made of military grade materials with waterproof dual seam technology and water repellent double coating. It adopts a genuine waterproof zipper, used in extreme weather! LARGE SIZE: Our roof bag was designed to solve the problem of limited storage space in the car. 15 cubic feet rooftop cargo bag allows you to hold 3-5 suitcases, travel luggage case, tents, sleeping bags and more. Free up inside vehicle space for more comfortable on the way. MOST SAFE DESIGN: For security reasons, we use 6 reinforced adjustable straps to keep the cargo carrier in place. In addition, equipped even in high speed road or bumb road, no slip, no scratch to your car. WORKS WITH or WITHOUT ROOF RACK: Use this car roof top luggage carrier with any sized car or SUV. It can be quickly and easily installed in minutes whether your vehicle has a rack installed or not. NOTE: All seams are heat welded and stitched to ensure they are watertight. that your luggage will stay safe and protected in all weather conditions during your travels. But please note that it's not 100% waterproof under rainstorm weather.