Instruct: Classify Amazon reviews into positive or negative sentiment
Query: What purpose does it serve?

After installing these it looked great on the car, but during the first rain it proved to serve no purpose. As installed per instructions (I understand there is room for error but this isn't my first deflector install), windows can not be left cracked if there is even a chance of rain because it'll just rain into the window. I bought this for somebody else, they like to keep windows cracked to smoke when it's raining, unfortunately for her she can't even get fresh air when its raining unless she uses the dash vents to get exterior air. Again, it's a 1 star because it doesn't do what it is intended to do.