In other words, make sure you try it on the passenger side first.If you've never polished glass, be ready for an exercise in frustration, agony and time wasting. It's an extremely difficult task. The idea that one can remove minor scratches by EASILY polishing off a small quantity of the surface is really wrong. Glass is exceedingly hard to grind down and requires powerful tools, the proper compounds and methods. Failure at any step leads to poor results.