I posted this within another thread, but not sure that it will get answered there.

What is the point behind the brillo in the crack pipe?

The brillo serves as a screen.

It's also very dangrous. Don't let the "clean and shien" purpose fool you. I had a friend burn his throat this way.

Brillo work as a "filter". It is also pushed from one side of the pipe opening to ther other to get all the residue off the glass to it can be smoked.