Here's what mine looks like:
And here's what it looks like when the sanitizer chamber is open:
Along the top of the chamber, there are two buttons—one green and one white, and which you can see in the two images above—the white one simply opens the chamber door, and the green one starts the sanitation cycle. Between the two buttons, there's in inscription that says, "UV clean."
"Yeah, yeah, so what's the point?" you ask. Well, it's more of a question than a point.
I am seeking to understand how all that crud—that you can see in the image below—builds up in a chamber whose sole function is to sanitize your brushes to a "UV clean" state.