It's really just kind of the disk method where you're gutting out the inside of a disk. So that's the inside of our washer, and then this is the outside of our washer. Outside of our washer looks something like that. Hopefully that makes sense. And so the surface of our washer looks something like that. I know I could have drawn this a little bit better, but hopefully it serves the purpose so that we understand it. So the surface of our washer looks something like that, and it has depth of dx.