Air deflectors which are also called wind deflectors, are generally designed to prevent rushing air to enter your vehicle when certain parts of the car are meant to be open. But because of customization and modern vehicle designs, the air deflector's design was taken to new heights. Some of these were made just to be cosmetic and for restyling. But most of air deflector's designs were improved. They now come in different designs and make - and they also come for different purposes. Some air deflectors are crafted to prevent rain from seeping into your side windows. There is another type of air deflector that functions as a sunroof air deflector which look like a small spoiler that is mounted in front of your sunroof that reduces wind noise and buffeting. This kind of air deflector also keeps your vehicle clean from dust. There are rear window air deflectors that also keep your vehicle dust-free.
Like rear window air deflectors, there are also bug shields that primarily keep your car's windshield and finish clean from insects. When you're driving at night, it's very likely to splatter bugs on windshield. Bug shields prevent this by aerodynamically deflecting bugs off your windshield.