The eyebrows also look to be interchangeable with the mustache. Interchangeable parts.
What is most remarkable is that his eyebrows can move down below his eyes. Yes, he can move his eyebrows down so that he can peek over them, and he does this when explaining the unexplainable to that nitwit Bob Scheiffer.
I think there was a muppet with similarly mobile, autonomous eyebrows. I'm not sure. I know I've seen the arrangement before, and on a puppet. It is a new twist to see such facial gymnastics on the puppeteer.