20 Cubic Feet - Carrying capacity - The whole point of the purchase us to provide additional cargo room, so it makes no point to buy one that is not big enough. the roof bag overall size is 51.1'' x 39'' x 17'', Carry 20 cubic feet. Larger than other brand. Soft Car Top Carrier - There is no ”Best Soft Car Top Carrier”. Instead, the best one is the one that satisfies your specific needs.However, we provides the best all-around value and is likely to satisfy more consumers. We provides larger capacity ( 20 Cubic ), top PVC material, convenient design and more security. Easy Mounting & Storage Design - Design with 6 short tie straps & 2 long straps, make it easy to attaches in only a matter of minutes. Our Carrier is purely malleable, more simple to store than the carrier with stiff inner-lining ( storage bag included ). Waterproof - PVC Materials - The torrential downpour will test merely water resistant materials to their limit and likely result in damp or soaked contents. But our car top carrier is coated with PVC to aid in waterproofing ( inside and out ),NOT ONLY WATER RESISTANT like other brand. 6 Tough Straps - More Security- Alongside carrying capacity, stability is arguably the most important factor in a car top carrier. We Provide 6pc wide straps & 2pc 3M straps. To some extent, the more straps used to fasten the carrier to the roof the better.