As many people have heard, the black anondized coating on the sides of the iPhone 5 scratches a bit easier than anticipated. We've done our best to make it so our case does not scratch the sides of the phone. Our case barely touches the two anondized rails, and instead glides along the the flat edge next to the screen of the phone.
Please keep in mind, just like any hard case, debris trapped between the phone and case may cause scratching. Make sure to brush debris from the phone and the inside of the case before putting it on.