What is that thing? Is it a Frisbee? a stepping stone? a shield? It's an ingenious tool to help keep scratches and swirls from damaging your paint. Put in bottom of a bucket, as seen below, allows the dirt and grit to settle at the bottom of your wash bucket, thus making it less likely that it will get caught in your wash sponge or mitt.
This works best using the two bucket wash method.
Where do I get it? Click here to go to the manufacturers website directly.
For more information on washing with two buckets please the following article provided by eShine.