This is a Meguiar's wheel brush (I forgot the actual name of the product, but it's by Meguiars). I use that to clean in the nooks and crannies of the wheels. I think it does a pretty good job at it too. The best part is that the tip itself is slightly bendable so it can go around to the backside too and around the brake calipers. They might be discontinued though, so I'd look around for something like it.