Peugeot207: Whispbar Flush bar S23W + K466 Fitting Kit, mounted Rocket Box Pro12. Cargo Capacity: 340 litre. The RocketBox Pro 12 is great for shorter roofs, sedans or larger-vehicle owners who have stuff that they don't want to carry inside the car. Somehow we found out how to make this cargo box compact and spacious at the same time.