【Multi Levels Waterproof】1st level: 500D(denier, fineness of chemical fiber) waterproof material which resists most rain, storm, snow or dust; 2nd level: 4-inch zipper flap isolates water from zipper; 3rd level: 8 velcros tightly connect zipper flap with the bag and thus prevent exposure of zepper; 4th level: waterproof zipper assures left small portion water won't damage your goods; 【Reinforced Straps & Hooks】This car bag is especially designed with 10 straps and 6 hooks for more stability, which allows you to carry your baggage for longer distance; 【Large Capacity for Various Cars】It suits most style of cars, with or without racks; 15 cubic feet capacity can load 2*20-inch suitcase, 2*24-inch suitcase, 6*sleeping bag and 2*4-person tent; perfect for family outing; 【Easy Installation & Storage】Fasten 10 straps on your car racks or stuck 6 hooks on your doors for installation; when not in use, you can store it in portable bag which is 15.4*4*11.8 inches; 【You Can Get】1*15 cubic feet roof bag; 1*portable storage bag; 1*anti-slip mat; 6 hooks; 1*user manual.