The name says it all - it's an Auto Cup Holder Coaster. In other words, you put this into the bottom of your cup holder so that any of the humidity that gathers on your cup/tumbler, etc., can fall onto this keeping your cup holder nice and clean.
But more importantly than clean, it's stylish. We think it adds the perfect flair to your ride so that you can rep your favorite travel center while you cruise.
It also has a ring that you can cut off, in case it needs to be resized for other cup holders in your vehicle.